3. LOCATING SAMPLE DWELLING UNITS

3.1 Introduction

RTI statisticians are responsible for selecting the sample dwelling units (SDUs) to be contacted. For the NSDUH, approximately 200,000 sample dwelling units (SDUs) are selected throughout the entire United States each year.

What is a Dwelling Unit, or DU? If you think of all types of places a person could reside, those places are called dwelling units. Examples of dwelling units include the most common type, housing units (apartments, homes, trailers, condos), as well as individual units within group quarters structures (college dormitories, homeless shelters, convents). Other types of homes which are not included in the NSDUH sample are military housing (barracks, ships), various residential institutions (nursing homes, prisons), and some transient living quarters (hospitals, overnight hotels).

For the purposes of the NSDUH, we define dwelling units as housing units and group quarters units. When we refer to a DU, the procedure being discussed applies to both housing units and group quarters units. Any procedures that apply only to one type of unit will be clearly specified. Brief definitions of the three terms follow:

• dwelling units (DUs) – a generic term referring to both housing units and group quarters units
• housing units (HUs) – a group of rooms or a single room occupied or intended for occupancy as separate living quarters
• group quarters units (GQUs) – generally, any single living unit within a group quarters structure in which ten or more unrelated persons reside.

More detailed definitions of HUs and GQUs are provided in Sections 3.4.1 and 3.4.2.

An area probability sample design has been used to select the sample dwelling units needed for the NSDUH. Land areas and dwelling units were scientifically selected using Census Bureau estimates of population and housing unit counts to ensure the sample represents the United States' population.

For NSDUH, all of the 50 states and the District of Columbia have been divided into FI Regions, with 48 regions in each of the eight most populated states (CA, TX, FL, NY, OH, PA, MI, IL), and 12 regions in each of 42 states and the District of Columbia, for a total of 900 FI Regions. In each FI Region, eight segments (with boundaries usually defined by surface features such as streets, railroad tracks, and rivers) were selected, two segments for each of the four quarterly data collection periods.

Once the segments were defined, FIs were assigned to count and list the dwelling units in each of the 7,200 segments. The units were recorded on the List of Dwelling Units and, if applicable, the Group Quarters Listing Form. Information on these forms identifies an address or description for each housing unit and group quarters unit located within the boundaries of the segment. From these listings, specific HUs and GQUs have been selected for each segment. These selected HUs and GQUs are called sample dwelling units (SDUs) and make up your assignment in the segments you will be working.

As an FI, you are responsible for the final steps of the sampling process:

1. inspecting your segment materials
2. locating the segment and the designated SDUs
3. determining that each SDU is either a true HU or GQU
4. checking for missed HUs and GQUs.

These steps are explained in detail in this chapter.

3.2 Inspecting the Segment Materials

For each segment in your assignment, you will receive a packet of materials for the segment. This packet contains the materials listed in Exhibit 3.1.

Each quarter, each FI Region will have two segments—one from the prior year, only with different households selected, and one new segment. Because of these cycles, you will continue to see "NHSDA" while the new name and acronym are phased into use on the maps and segment materials.

The segment number found on all the segment materials identifies the segment and the quarter in which the segment is to be worked. Since NSDUH is implemented on a quarterly basis, each SDU must be contacted in the quarter for which it was selected.

Before any field work is begun, you will need to review all items in the segment packet to familiarize yourself with the location of the segment and the characteristics of the area. During field work, continually check the maps and materials to be sure you have located the correct selected dwelling units. When field work is completed, check with your FS for directions on what to do with the segment materials.

	MAP SET
County Locator Map (Exhibit 3.2)	...is used to determine the general location of the segment within the county; the census tract(s) containing the segment will be shaded. (A census tract is a land area with a population of about 4,000 that has identifiable boundaries on all sides.)
Census Tract Locator Map (Exhibit 3.3)	...shows the location of that tract(s) within the county, as well as the segment's location. Specific roads (boundaries of the tract(s)) are labeled to assist in locating the general "neighborhood."
Segment Locator Map (Exhibit 3.4)	...shows the actual segment boundaries within the tract(s); again, the segment is shaded. (The meaning of the symbols used for designating the different types of segment boundaries will be found in the legend of the Segment Locator Map only.)
Block Listing Map(s) (Exhibit 3.5)	...used to locate the actual dwelling units in the segment which have been selected for screening and possibly interviewing. Depending on the size of the segment, this may be one or more pages. For segments with multiple pages, a Page Index Map shows how the multiple Block Listing Maps fit together. You may also have a Zoom map, which is an enlargement of a specific area on a Block Listing Map. If certain streets are too close together on the map to allow the lister to accurately record the location of each SDU, a Zoom map enlarges the area so the precise location can be noted. There may be one or more pages of Zoom maps, labeled Zoom 1 of 3, Zoom 2 of 3, etc. The lister may have hand–drawn an enlargement sketch of a specific area as well.
COMPUTER GENERATED FORM LISTING ALL SDUs FOR THE SEGMENT
Selected DU List (Exhibit 3.6)	...lists all selected HUs and GQUs as well as each next listed line in the segment. (Selected lines are shaded, the next listed lines are unshaded.)
COPIES OF ORIGINAL COUNTING AND LISTING MATERIALS
List of Dwelling Units (Exhibit 3.7)	...photocopy of original handwritten list of DU addresses and/or descriptions.
Segment Information Sheet (Exhibit 3.8)	...contains helpful comments about the segment made at the time of listing.
Group Quarters Listing Form (Exhibit 3.9)	...photocopy of original list of up to 30 group quarters units.
Group Quarters Continuation Listing Form (Exhibit 3.10)	...continuation for a structure with more than 30 GQUs (if necessary).
Within–Structure Floor Sketch Sheet (Exhibit 3.11)	...sketch, included if necessary, showing layout that corresponds to the way the GQUs were listed.

The Locator Maps provide you with a general idea of the location of the segment by showing the surrounding geographic area. The County, Tract, and Segment Locator Maps are produced using 1990 Census data. Local maps, such as county highway maps or city maps, are sometimes needed to help locate the segment. If necessary, the person listing the segment may have obtained such a map locally. If so, it will be in the segment packet and should be returned with all other segment materials when work has been completed.

The Block Listing Map(s) show the precise location of each dwelling unit (DU) within the segment. This detailed map of the segment area was used by the individual who completed the listing to mark the exact location of each DU. Boundary and internal roads or streets and other significant features are clearly identified. Each segment may have one or more Block Listing Maps, depending upon the size and geographic make–up of the segment. The page numbers of the various maps are in the lower right hand corner. For segments with multiple Block Listing Maps, a Page Index Map is included in the segment packet which illustrates how the various maps fit together to form the segment.

When looking at the single page Block Listing Map illustrated in Exhibit 3.5, note the different symbols:

• an "X" for a single HU structure
• a box with a number inside indicating the number of HUs contained in a multi–unit structure
• a circle with "GQ" inside indicating group quarters.

Also note that the symbols on the sketch are cross–referenced to the List of Dwelling Units with the DU line number above the symbol. For example, an "X" with the number "3" above it on the Block Listing Map represents the location of the HU listed as line 3 of the List of Dwelling Units (see Exhibit 3.7); a circled "GQ" with the number "25" above it represents the location of the group quarters structure listed as line 25.

At times, it may have been difficult for the person who did the listing to fit several individual "Xs" on the map, especially if they are close together. In these cases, you may find a row of single family homes designated by two "Xs" connected by a bar with the corresponding line numbers printed above as in this example:

37—12
X—–X

In some instances, the Block Listing Map(s) did not give the lister adequate room to accurately record the DU locations. If so, Zoom maps are usually included. A Zoom map is an enlargement of a crowded or illegible area of a Block Listing Map. By following the numbering sequence of DUs, you can determine where the lister switched from the Block map to the Zoom map. Sometimes a Zoom map was not used and the lister created a sketch on a Block Listing Map Enlargement Form. Throughout the rest of this chapter, a reference to a Block Listing Map implies the inclusion of any enlargement sketches or Zoom maps.

The Block Listing Map is an important aid in identifying sample dwelling units (SDUs). Become familiar with it before beginning work in your assigned segment. Then, carry it at all times for reference to ensure you are properly identifying SDUs. Remember, the units selected for the study are chosen by their line number, NOT by their address. The address merely helps describe the location of the selected unit. Since the locations of all units are marked on your Block Listing Map, think of it as a treasure map where "X marks the spot." Use your maps while working to be sure you have found the proper "X" and are contacting the correct SDU. If you find a discrepancy between the location and the address, contact your FS for further instructions.

Although all DUs in a segment are listed on the original, handwritten List of Dwelling Units, only certain ones have been selected for you to contact for NSDUH screening. These selected DUs are printed on the Selected DU List (Exhibit 3.6) in the grey shaded lines. Note that also listed on this form is the address or description of each DU immediately following the selected DU (the need for this will be explained later in this chapter).

The Selected DU List provides a complete list of housing units and group quarters units selected in a segment. The SDUs are listed in numerical order by address or, if an address was not obvious, a description allowing you to identify the structure. On the computer–generated list, only a portion of the description may appear. In some instances, you may need to refer to the copy of the original List of Dwelling Units (Exhibit 3.7) for a complete description. A list of abbreviations that might have been used in this description is shown in Exhibit 3.12.

COLORS BG BK BL BR DK GR GN LT MED OR PK RD TN WH YL Beige Black Blue Brown Dark Gray Green Light Medium Orange Pink Red Tan White Yellow	DIRECTION/ORIENTATION ABV ACR ADJ BCK BEH BTWN BTM E FRT L N NE NW RE R S SE SW W Above Across Adjacent Back Behind Between Bottom East Front Left North Northeast Northwest Rear Right South Southeast Southwest West	ARCHITECTURE/BUILDING STYLE APT CPCD CLNL CONDO CNTP DBLWID DPX RCH RF SPL TRAD TRLR TRANS Apartment Cape Cod Colonial Condominium Contemporary Doublewide Duplex Ranch Roof Split Level Traditional Trailer Transitional
ADDRESSES ADD ALY APT AVE BLK BLVD BLDG CIR CT DRWR DR HWY JCT LN PKWY PL PT PO RD RTE ST TER WAY Address Alley Apartment Avenue Block Boulevard Building Circle Court Drawer Drive Highway Junction Lane Parkway Place Point Post Office (Box) Road Route Street Terrace Way	STRUCTURE/MATERIALS ALUM BRK BRNSTN CDR CBLK CEM LOG RCK SDG STN STU VNY Aluminum Brick Brownstone Cedar Cement Block Cement Log Rock Siding Stone Stucco Vinyl	TYPES OF ROOFS: FLT GBL GMBR HIP MNSD SHGL SPNTL TIN Flat Gable Gambrel Hip Mansard Shingle Spanish Tile Tin

OTHER/GENERAL
ATT BSMT BUS CPT CG CHNLNK CHMY CHUR COL COR CO DB DRMR DBL DRWY ELCMTR ENT EXT EXTR FEN FLR FDN FRM FR GAR GRD Attached Basement Business Carport Cattleguard Chainlink Chimney Church Column Corner County Doorbell Dormer Double Driveway Electric Motor Entrance Exit Exterior Fence Floor Foundation Frame From Garage Guard	GRV GRND HSE LG MBX MID MI PKT PCH PVT RR RSTR RM SCRN SHK SHUT SD STR STY TR UC VAC VER VEST WIN WD Gravel Ground House Large Mailbox Middle Mile Picket Porch Private Railroad Restaurant Room Screen/Screened Shake Shutters Side Door Store Story Trim Under Construction Vacant Veranda Vestibule Window Wood

Keep in mind the Selected DU List contains all selected DUs for the quarter. Sometimes assigned cases are released in batches or partitions, so that not all SDUs on the Selected DU List are available to be worked. The partition to which each SDU is assigned is indicated in the last column on the Selected DU List. When additional lines do become available, your FS will tell you and you will receive the lines on your Newton via a transmission.

If any group quarters were listed in a segment, a copy of the Group Quarters Listing Form is included in the packet of segment materials. The Group Quarters Continuation Listing Form is included if the group quarters structure contained more than 30 units. The Within–Structure Floor Sketch Sheet will be included only if the description of the unit on the listing form is not sufficient to locate it.

Because screening for the NSDUH is electronic, you will have no need for a paper Record of Calls or any type of contact worksheet. While visiting an SDU, if you need to make any notes that you cannot enter into the Newton, you may do so on your segment materials.

3.3 Locating the Segment and the Designated SDUs

The general location of a segment and the most efficient route of travel to reach the area should be determined during your careful, advance review of the segment materials. When you arrive at the segment, first double check that you have identified and located the precise boundaries of the area, that the proper area was listed, and that it was listed correctly. (For segments covering large geographic areas, first talk to your FS about your initial trip.) Referring to the locator maps, Block Listing Map, and Selected DU List, check to be sure that you are in the exact area and that the lister correctly identified the area.

If you determine that the wrong area has been listed, if there are serious omissions or inaccuracies in the listing, or if there are significant changes to the area (such as a new subdivision or apartment building), do not proceed any further. Call your Field Supervisor immediately.

Once you are in the exact segment location, you will begin identifying and contacting only designated Sample Dwelling Units (SDUs). In most cases, you will be able to find them with little difficulty by using the Block Listing Map and the Selected DU List. In some cases, however, you will have to check more thoroughly and refer back to the original List of Dwelling Units. For example, if you were using the map and list shown in Exhibits 3.5 and 3.6:

• HU #1 — One story white frame house on Riverdale Avenue. When you arrive at the segment and locate the corner of Riverdale Avenue and 236th Street, you do not see a white frame house. There is, however, a yellow frame house facing Riverdale Avenue a short distance from the corner, as indicated on the Block Listing Map. Checking around the corner of 236th Street, you find a house in the position indicated for HU #27 on the map. The next house south of the yellow frame house on Riverdale Avenue is a brick split–level house with a two–car garage, the description listed for HU # 2, in the location indicated for HU #2 on the Block Listing Map. Upon talking to a neighbor, you find that the house located between HU #27 and HU #2 was recently painted and had been white. The yellow frame house is HU #1.
• HU #12 — 943 235th Street. When you arrive you find that the street number is not clearly indicated on the mail box. You note that the number visible on the house immediately preceding on the east is 939, and the number 947 is seen on the next house to the west. You are sure that the street is 235th Street. The HU has been clearly and easily located by reference to the Block Listing Map, Selected DU List, and visible street numbers associated with existing structures.

In most instances, the dwelling unit you locate will be a housing unit, as in the examples above. However, you may encounter selected group quarters units as in Exhibit 3.6 (GQU line numbers B003 and B019). In this example, first locate the Salvation Army Shelter, which is the structure that contains the selected GQUs, using the Block Listing Map ("GQ" circled) and the Selected DU List, which shows the structure as "025." This line number is the number above the circled "GQ," which is the line number of the shelter on the original List of Dwelling Units. This number connects the selected units with the shelter in which they are located. After locating the structure, you then use the description of the unit (bed numbers 3 and 19) in conjunction with the Within–Structure Floor Sketch Sheet (Exhibit 3.11) to identify the correct GQUs.

For some group quarters units, the description of the unit alone may be sufficient for locating it (e.g., dormitory rooms with unique room numbers). In such a situation, a Within–Structure Floor Sketch Sheet probably would not be included with your segment materials.

3.4 Determining the Status of Each SDU

Only structures qualifying as eligible HUs or GQUs should have been listed. Since the individual completing the listing was not required to enter structures or talk to residents, it is possible that some listed structures may not qualify as an HU or a GQU or may be ineligible. You must determine the status of each SDU at the time of your initial screening contact.

It is your responsibility to make sure that the assigned address is (1) a housing unit (as defined below), and (2) only one housing unit. If either of these conditions is not met, appropriate action must be taken.

For purposes of this study, a housing unit is a group of rooms or a single room occupied or intended for occupancy as separate living quarters. A more detailed definition is given in Exhibit 3.13. Please refer to this more detailed definition before continuing to read.

A housing unit is a group of rooms or a single room occupied or intended for occupancy as separate living quarters; that is: The occupants do not live and eat with any other family group or persons residing in the structure AND There is either direct access from the outside or through a common hall. Direct access means there is an entrance directly from the outside of the structure to the living quarters, or an entrance to the living quarters from a hall, lobby, or vestibule used by the occupants of more than one unit. Living quarters do not have direct access if the only entrance is through a hall or room of another unit. Occupancy: A housing unit may be occupied by a family group or an individual living alone. It may also be occupied by nine or fewer unrelated persons. (NOTE: If ten or more unrelated persons occupy the unit, it is considered "group quarters" and is not to be treated as a selected housing unit.)

The following list of types of HUs, although not exhaustive, includes most types you may encounter:

1. A single house that is intended for occupancy by only one family.
2. A flat or apartment in a structure that includes other flats or apartments.
3. A basement or attic apartment in a structure that includes one or more other DUs.
4. Vacant houses or apartments that could be occupied.
5. Hotel or motel rooms that are (a) occupied by permanent guests, or (b) occupied by employees who have no permanent residence elsewhere.
6. Residential units under construction. (NOTE: The Selected DU List may include such a unit.)
7. Rooms within group quarters or an institutional structure (such as a fraternity house or nursing home) that serve as the permanent residence of a staff member or "house mother" and that satisfy the requirements of the HU definition.
8. An apartment in a nonresidential structure used as a permanent housing unit (e.g., an apartment in a warehouse that the caretaker uses for personal living quarters).
9. A mobile home or trailer used as the permanent residence of the occupants.
10. A mobile home or trailer location in a trailer lot or mobile home park in which numbered or otherwise specified spaces are rented. In such a mobile home park, each separate space allocated for one mobile home is listed as an HU, even if no mobile home currently occupies the space; that is, an empty space in a regular mobile home park is treated like a vacant apartment or house.
11. Work camps occupied by seasonal workers are considered permanent DUs if workers live there for half or more of the calendar quarter. Check the number of residents to see if the unit should be an HU or a GQU.
12. Seasonal dwellings, such as summer homes, resort cottages, or other part–time homes that could serve as residences.
13. Rooming or boarding houses. Determine the number of residents in the structure. If there are nine or fewer residents who are unrelated to each other, treat the structure as a housing unit. If there are ten or more unrelated persons, the structure is a group quarters. Group quarters are discussed later.

If you are ever in doubt as to how to classify a unit, contact your FS for clarification. Be sure to have your segment materials in front of you when you call your FS.

In general, the definition of group quarters is any single structure in which ten or more unrelated persons reside; also these persons must live and eat together, not separately. This definition could apply to any type of structure including houses, apartments, barracks, and dormitories. The actual group quarters units would be the rooms, beds, or individuals used to define the composition of the structure.

For this study, there are several instances where a structure is classified as group quarters regardless of the number or relationship of occupants:

• college dormitories, sorority, and fraternity houses
• quarters for live–in staff members of institutions (who do not live in actual housing units within the structure)
• missions and shelters.

The following list of structures, although not exhaustive, includes many examples of group quarters you may encounter:

1. A boarding house is a structure in which living space is rented to residents (boarders) who are served regular meals on the premises. Meals are furnished as part of the rental fee, which is usually paid on a weekly or monthly basis. Variations of boarding houses include:

   A rooming house is a structure in which living space is rented to residents (roomers) who may receive maid or linen service in addition to a room. Meals are not provided regularly.

   A combination boarding and rooming house is an establishment which serves meals to some resident persons (boarders) but only rents to others (roomers). The same listing rules apply to this unit as to boarding houses and rooming houses.

2. Communes, "Families," "Communities," etc. are a group of unrelated individuals who live together and pool their resources but who have no regular arrangements for contributing to expenses. Such groups may call themselves a family, a commune, an establishment, a community, a farm, a colony, etc.
3. Convents, Monasteries, and Other Religious Residences are considered group quarters if there are ten or more unrelated persons residing in them.
4. Facilities for Housing Students like fraternity houses, sorority houses, or student dormitories may be in the sample. Eligible individuals in such student housing facilities are always considered residents of group quarters, regardless of the number or relationship of the occupants. Please note that campus housing for married students and their families are considered housing units, not GQUs, since the occupants are related to each other.
5. Missions or Shelters and other structures of this type may contain living quarters for individuals who, although somewhat transient, have no other "permanent" place of residence. Missions or shelters are considered group quarters regardless of the number or relationship of the occupants.
6. Halfway Houses are places occupied by persons such as former prisoners, mental patients, or alcohol or drug addicts. The occupants may be there on either a voluntary or involuntary basis.
7. Institutional Staff Quarters should be considered as part of the group quarters, regardless of the number or relationship of the occupants. Residential quarters for caretakers, administrators, or other personnel that are permanent dwellings according to the housing unit definition, should be considered HUs.
8. Migratory Workers' Camp or Logging Camp consists of living quarters, or sites for living quarters, for ten or more seasonal or temporary workers engaged in agricultural activities (including related food processing activities) or in a logging operation. Such living quarters may be temporary in nature and may consist of structures, mobile homes (or sites), tents (or tent sites), vehicles, or a combination of types of living quarters.
9. Nonmilitary Barracks and Bunkhouses are structures that provide living space for a number of people, either in large general areas or in small sleeping areas or rooms.
10. Retirement Residences and Independent Group Residences for the Elderly, Handicapped, and Functionally Disabled are also included in the sample. These are non–institutional residences, such as foster homes and board and care homes, that provide a home environment for the elderly, handicapped, and functionally disabled as an alternative to institutional care. The occupants must own or rent their living quarters. Meals may or may not be provided. Some supportive services are offered, such as supervision of self–administered medication and diet, assistance with housekeeping, and arrangement of transportation and recreational activities. If there are ten or more unrelated persons residing in these units, they should be considered a group quarters. Services do not include nursing care, medical care, or psychiatric care by staff members; if these services are included, it must be considered an institution, thus making it ineligible.

If you are ever in doubt as to how to classify a unit, contact your FS for clarification. Be sure to have your segment materials in front of you when you call your FS.

Certain types of buildings should not have been listed. Those identified below, with the exception of permanent HUs or GQUs that may exist within them, do not qualify as DUs for NSDUH. If you encounter such units included as SDUs in your assignment, classify them with the appropriate code during screening.

• Specified Institutional Units:

–	correctional institutions
–	mental institutions
–	homes for mentally and physically handicapped children
–	nursing, convalescent, and rest homes
–	hospitals
–	other institutions that provide care for residents or inmates.

• Military Barracks on a military base.
• Unoccupied Structures that have been condemned or are being demolished.
• Places of Business, such as stores, factories, etc. (Be sure, however, to look for hard–to–find living quarters behind, above, or inside such places.)
• Certain Transient Living Units, such as transient hotels and motels for overnight lodging (such as Holiday Inns, Red Roof Inns, etc).

Exhibit 3.14 provides a chart identifying categories of dwelling units and their respective eligibility for the NSDUH.

DWELLING UNITS TYPES		Is This Unit Eligible for NSDUH ?
Housing Units (HUs)
Civilian (e.g., house, apartment, condo, townhouse, etc.)		YES
Military (e.g., family housing, civilian employee housing, etc.)		YES
Group Quarters Units (GQUs)
Noninstitutional	Civilian (e.g., rooming/boarding houses, dorms, fraternity or sorority houses, transient shelters, halfway houses, migratory workers' camps, etc.)	YES
	Military (e.g., barracks, ships, etc.)	NO
Institutional	Civilian (e.g., correctional institutions, nursing homes, mental institutions, etc.)	NO
	Military (e.g., VA Hospitals, military prisons, etc.)	NO
Certain Transient Living Units
Civilian (e.g., General hospitals, transient [overnight] hotels and motels, etc.)		NO
Military (e.g., Military barracks, transient visitor housing, etc.)		NO

3.5 Checking for Missed Dwelling Units

Although those involved in completing the listing made all reasonable efforts to be sure every dwelling unit in a segment was listed, the lists may not always be completely accurate. There may have been some dwelling units the lister could not observe because of their location, mobile homes may have been moved into the segment, a new house may have been built, or what appeared on observation to be one type of unit may be entirely different when one is inside the structure. Every dwelling unit must have a chance of being selected for interview. However, if it was not listed, it has no chance of being selected for an interview unless the dwelling unit is discovered by the interviewer. The missed dwelling unit procedures, which you must follow carefully, are designed to give that opportunity to those dwelling units that should have been listed but were not.

This task is particularly important, and the procedures for checking for missed dwelling units are fairly simple. The rules for checking are slightly different depending on whether the listed unit is a:

• group quarters unit in a group quarters structure (dormitories, shelters, boarding houses),
• housing unit in an apartment building or condominium structure, or
• regular housing unit not included above (such as a single–family home, townhouse, trailer, or duplex).

You are not required to check the entire segment for missed dwelling units. The procedure only requires that you implement the check for missed DUs for every selected dwelling unit in the segment. Therefore, when you are conducting screening, implement this check for each SDU you visit.

NOTE: Although you are only required to check for missed DUs for each SDU, you should not ignore any significant listing problems. For example, if you discover an apartment building or a new subdivision that was not listed, call your FS.

To check for a missed dwelling unit, first check for missed DUs within the actual housing unit. One of the first questions during the screening process requires that you ask at every regular HU that is not a condo or in an apartment building if there are any additional living quarters in the unit. Examples of the types of missed DUs you may find within an individual SDU are:

• a basement or upstairs apartment built in a structure that was originally a single–family dwelling, with an outside entrance in the rear of the structure that could not be observed by the lister
• an apartment with an entrance in the rear of a large townhouse that the lister missed
• an additional unit behind what looks from the front to be a standard duplex.

Ask this question for regular housing unit structures such as single–family homes, trailers, cottages, townhomes, and duplexes. Although this includes both individual structures and multi–unit structures (townhouses/duplexes), there is a stronger likelihood of missed units in structures like townhomes so the question must be asked. Housing units that are in apartment and condominium buildings are handled differently, as are all structures with selected group quarters units (see Sections 3.5.2 and 3.5.3).

The other missed DU check is to check the geographic interval between the SDU and the next listed dwelling unit to determine if there are any unlisted DUs. In a street of single family homes, you would check the property of the selected DU and the space between that unit and the next listed unit. Look for attic, barn or garage apartments, trailers or mobile homes, and roads or driveways not marked on your map that exist between the SDU and the next unit the lister recorded. This is the main reason why the Selected DU List shows the selected lines plus the next listed line. The phrase "next listed line" can refer to two situations:

• Usually, the next listed line is the line number of the unit that follows the SDU. For example, if you contact the SDU at line number 156, the next listed line is 157.
• Consider a segment with multiple map pages. During the listing stage, the lister completed the work one map page at a time. Your search for missed DUs must also progress one map page at a time. If an SDU is the last listed line on a map page, the "next listed" line is the next one listed on that map page—which is simply the first line listed on that map page thus closing the 'circle' on that page.

In other words, for cases where you are contacting an SDU that is the last one listed on a map page, the next line listed is the next one on the page (the first one), not the next listed line numerically. The geographic interval is then defined as the area between the last line on the map page and the first line on the map page.

Normally, the geographic interval between an SDU and the next listed dwelling unit is a short distance. In fact, for townhouses, it often is a few feet between doors. Sometimes in rural segments, however, the DUs may be far apart. It is important that you follow the travel pattern used by the original lister in checking the interval. This pattern should be indicated by directional arrows drawn on the map; if not, determine the pattern from the sequence of dwelling unit numbers. The lister should have followed a prescribed order (see Exhibit 3.15), traveling around the segment in a clockwise direction, making each possible right turn at internal streets or roads and listing dwelling units as they appeared on the lister's right. However, regardless of whether or not the lister followed the prescribed order of listing, follow the same travel pattern the lister used.

There is a special situation which you may encounter infrequently in some of the rural areas with large segments and many map pages. If an SDU is the last one listed on a map page and the map page that follows it has no DUs listed, you must check not only the geographic interval between the last listed DU and the next listed line (which is the first line listed on that map page), but you must also check the entire zero DU map page that follows and any subsequent zero–map pages. This ensures complete coverage and improves the quality of the NSDUH data by enhancing its statistical accuracy. A note on the Selected DU List will notify you of any zero map pages to check.

NOTE: represents the starting point.

The missed DU procedures for apartment buildings and condominium structures vary from the regular housing unit procedures, but you will still check for missed units within the unit/structure and in the geographic interval.

• WITHIN the UNIT

  Most apartment and condo buildings consist of a number of single units within the multi–unit structure. In these buildings, the chances of finding a "unit within a unit" are very small, so you are not required to ask the missed DU question during screening. However, to ensure our sampling is accurate, we have to allow for unusual situations such as a servant's unit within a large apartment or flat. This does not mean a missed superintendent's apartment within the apartment complex, but an apartment that has a second separate unit within the apartment. If you are working in a building where this unusual situation is possible, be especially observant. If you discover an apartment within an apartment at a selected DU, you can add that unit to your Newton (see Section 3.6).

• WITHIN THE STRUCTURE /ON THE PROPERTY

  As you start working an apartment or condo building where an HU has been selected , also look for missed DUs at the structure level. Conduct a global check of the original listing to make sure it is accurate. Walk around the structure, comparing what you find with the handwritten List of DUs. Look for discrepancies like a missed floor, a missed wing of a building, or other groups of units that were missed.

  If you are talking to a knowledgeable person such as a building manager because of access issues, you may review the original listing for accuracy with that person. (Be sure to check with your FS before approaching management.) If you discover any missed units, gather the necessary information and check with your FS. Depending on the number of units, RTI's Sampling Department may choose a subset of units to be added or may ask that the entire structure be relisted and then resampled.

• GEOGRAPHIC INTERVAL

  Remember to also check the geographic interval between the structure and the next listed structure to look for missed units. Be observant.

In general, missed units found in an apartment or condo building must be added with input from RTI's Sampling Department. Gather the relevant information and then call your FS.

For selected units within group quarters structures, the checks for missed DUs occur at the structure level, not the selected DU level. For all group quarters structures where a GQU has been selected, you must check with the manager, landlord, or other knowledgeable person to determine if the number of units originally listed is accurate. If the number is larger, those additional units become missed units. This situation may occur if:

• the lister missed basement rooms in a dormitory
• the number of persons or beds in a shelter has increased for the winter season.

Reviewing the original listing with a knowledgeable person should uncover any units that may have been missed within the structure or on the property. Remember to also check the geographic interval between the structure and the next listed structure to look for missed units. Be observant.

Missed units found in a group quarters structure must be added through RTI's Sampling Department. Gather the relevant information and then call your FS.

If there is an entire group quarters structure that was not listed, it is considered a missed dwelling unit and the units within the structure, missed group quarters units. Unlike missed housing units, a missed group quarters structure does not have to be linked to (that is, "found at") a selected dwelling unit. Such a structure qualifies as a significant listing problem that must be discussed with your FS.

While we want you to add any missed or new DUs you find, do not make any deletions from the list of DUs. On occasion you may discover that a listed SDU does not qualify as a dwelling unit (e.g., a structure that is used for nonresidential purposes). You also may encounter a situation where an SDU no longer exists (e.g., a trailer that has been moved). In such cases, do not delete the unit from the List of Dwelling Units or attempt to remove the unit from the Newton. Rather, code it appropriately on the Newton during screening and proceed normally with the check for missed DUs. Chapter 4 defines the screening result codes.

3.6 Adding Missed Dwelling Units

The procedures for adding missed DUs differ slightly for missed HUs and for missed GQUs.

If you discover a previously unlisted HU within or on the property of an SDU or within the interval between an SDU and the next listed DU, record the address or description in the Newton. Be certain the unit qualifies as a housing unit. Apparent housing units used for nonresidential purposes (e.g., business or storage) do not qualify and should not be added. Missed housing units intended for use as residences but vacant at the time of your visit are to be added. Units under construction are to be added if construction has reached a point where all exterior windows and doors are installed (so that it is not open to the elements) and useable floors (such as sub–flooring) are in place. You may even find a missed housing unit within a group quarters structure, such as a "house mother's" apartment within a fraternity house.

At the beginning of each screening with an adult resident of the DU, ask the question used to identify missed DUs if you are visiting a regular HU that is not in an apartment or condo building.

If the answer at a regular housing unit is "No" you will continue with the screening process. If "Yes," you will record the address of the possible missed unit.

If the SDU is in a multi–unit structure such as an apartment or condo building, do not ask the question for each unit, but continue with screening. (See Section 3.6.5 for how to add any found 'units within units.')

Enter the street address or description of the missed unit. Only use letters, numbers, spaces, periods, commas, or slashes (as in 305 1/2 Main Street) not other characters such as quotation marks.

• Tap Cancel DU if you want to cancel this entry.
• Tap Update Record to continue the process of adding the unit. You will be asked if you want to add another unit. Tap Yes if you want to add another unit and the above screen will reappear so you can enter the information. Tap No if that is the only (or last) added unit you want to link to this SDU.

There are limits on the number of missed units you may add on your own in the Newton. You can link up to five added units to one particular SDU, while the limit of missed units for a particular segment is ten. You will rarely find more units than these limits. If you find more than five units for one SDU or more than ten units to add for a segment, record the information about these missed units on the List of Added Dwelling Units (Exhibit 3.16). When the information is complete, check with your FS, who will then call RTI's Sampling Department.

NSDUH – Project 7190 Survey Year ________	Page 1 of ______
LIST OF ADDED DWELLING UNITS

SEGID__________________ FI_________________________ FI ID No.____________ Date____________
DIRECTIONS TO FI The Newton allows you to add up to 5 added HUs at a specific DU or 10 HUs to the entire segment on your own. As you add the units for this segment in your Newton, record in the below columns: The Line Number assigned by the Newton The Address and/or a description of the added DU An Apartment Number or location The Link Line # which is the number of the SDU (from the List of Dwelling Units) the Added DU follows Whether the Added DU is an HU or a GQ (group quarters structure). Keep track of all Added DUs on this form. In some cases you will need assistance from RTI's Sampling Department to know exactly which DUs to add. Complete this form (leaving the Line Number column blank) if you find: More than 5 missed HUs linked to a particular DU More than 10 missed HUs in the entire segment An entire missed group quarters structure If you find individual group quarters units that have been missed, complete the separate Added Group Quarters Listing Form. When the forms are complete, call your FS, who will contact RTI's Sampling Department.
1	2	3	4	5
Line (DU) Number	Street Address, RFD Number, and/or Dwelling Unit Description	Apartment No. Or Loc.	Link Line # (No. Of SDU which Added DU follows)	HU or GQ

9/09/2002

Because this happens infrequently, your Newton will initially only have room to add five missed DUs per segment. If you need the additional five lines, contact your FS, who can ask RTI to release the additional lines to you during your next transmission. Each time you add a missed DU, your Newton reminds you of how many lines are still available, which should help you decide when to contact your FS about releasing additional lines.

The simple process of reconciling Missed DUs involves answering a few questions when prompted by the Newton to see if the missed unit you recorded should be added to the sample.

The instructions on this screen remind you to double check the original, handwritten List of Dwelling Units (Exhibit 3.7) to see if the unit has already been listed. When asking respondents about additional units on their property, they may report a unit that was indeed already listed. If the unit is already on the List of Dwelling Units, it does not need to be added, so you would tap Yes and then continue. If the unit is not on the List of Dwelling Units, tap No.

Missed units not on the List of Dwelling Units must satisfy location requirements before being added. This screen prompts you to consider the location of the missed unit.

• Is it within the SDU?
• Is it within the area or geographic interval between the SDU and the next listed DU? This interval includes additional units on the property or within the area between the SDU's property and the next listed DU. For an SDU that is the last one listed on a map page, tap the i–box for additional instructions.

If the unit is within the SDU or in the appropriate geographic interval, tap Yes and the unit will be added to the sample. If the answer is "No," the missed unit address will not be added.

The complete address of the unit to be added is displayed on this screen for you to double check. Make any necessary changes, then tap All Correct – Add Unit. The unit will be added to your assignment using the Case ID number displayed on the screen. The line number is the last 3 digits of this Case ID. Use the information on this screen to record the unit on the List of Added Dwelling Units (see Exhibit 3.16). All added dwelling units are recorded on this form, which becomes part of the segment materials.

Each time you add an HU and record it on the List of Added DUs, you must also enter a corresponding "X" (or box, in the case of multi–unit structures) in the appropriate location on the Block Listing Map. Remember to identify the symbol with the dwelling unit number provided by the Newton.

Exhibit 3.17 illustrates how the Block Listing Map would look if an unlisted HU were discovered in the interval between HU # 3 and HU # 4 in the segment illustrated previously in this chapter. Note that you should record the line number of the added HU on the map. This number is automatically assigned and then displayed by the Newton and recorded on the List of Added DUs in column 1. Be sure to give the information to your FS to update the FS set of segment materials as well.

Unlike housing units found at regular housing units, you do not add missed units found in group quarters structures to the Newton and then automatically screen them. Since the selection process for these missed units varies depending on the type and number of missed units (e.g., a boarding house versus a shelter), you are required to call your FS who then contacts RTI's Sampling Department to receive instructions on how to proceed. Be sure to have your segment materials as well as a thorough description of the missed unit situation in front of you when you contact your FS. In general, you will find out:

• what information to include on the Added Group Quarters Listing Form (Exhibit 3.18)
• whether to make a within–structure floor sketch
• what forms to send to RTI.

The information sent to RTI is used to select the missed units, if any, that are added to the sample. The assignment of any missed group quarters units that are to be screened takes place during transmission. The added cases are sent to your Newton for completion.

The procedures for dealing with missed units found in apartment or condo buildings vary depending on the situation:

• If you find a unit within a unit, (such as a servant's quarters within a large flat) that missed unit must be added to your Newton. This is not done during the actual screening but either before or after from the main Select Case screen. For details, see Section 6.9.1.
• If you find a unit or units within the structure, on the property, or in the geographic interval, you must contact your FS. Similar to the situation for missed units in group quarters structures (see Section 3.6.4), your FS must contact RTI's Sampling Department for instructions on how to proceed. Be sure to have all your segment materials and a thorough description of the situation.

The detailed process of adding missed DUs is not a task you will have to perform very often. When faced with a missed DU situation, be sure to consult these sections of the manual and discuss the situation thoroughly with your FS.

3.7 When to Call

If you encounter missed units or unusual circumstances and cannot find answers in this manual, call your FS. Your FS is experienced in many field situations and can assist you. In some instances your FS will need to call RTI's Sampling Department for assistance.

Your FS will call RTI when:

• more than five missed HUs are discovered to be linked to a particular selected DU
• more than ten missed HUs are to be added to the segment
• a missed HU (other than a unit within a unit) is discovered within an apartment or condo building
• a missed GQU is discovered within the group quarters structure
• a missed group quarters structure is discovered.

Once the issue is resolved, detailed instructions will be relayed to you.

3.8 Importance of Sampling Activities

The field sampling steps discussed in this chapter are important. All aspects of the area probability sample design used by RTI have been developed so that data collected for this survey will be valid, reliable, and accurate. However, the design is only valid if each interviewer carries out the final steps of sampling with care and precision. Even seemingly slight errors or oversights in interviewer sampling activities may necessitate costly and time–consuming corrective action.

Careful attention to the instructions presented in this chapter will provide the necessary information to complete the steps involved in checking the listing. Those steps are extremely important to ensure the accuracy of the sample and the data collected.

To assist your learning process, read the following summary of key points in this chapter. Following the summary are several questions to ask yourself. These questions will help you identify those areas you understand, and pinpoint the areas where you would benefit from re–reading a particular section.

• Dwelling Units (DUs) consist of housing units (HUs) and group quarter units (GQUs). Common examples of HUs are apartments, houses, trailers, condos. Individual units within group quarters structures such as college dormitories, shelters or convents would all be classified as GQUs.
• For this year's sample, all 50 states and the District of Columbia have been divided into 900 FI Regions. Each FI Region then had eight segments selected. Each FI will be working in a defined segment, using listings and maps that were created earlier by field listers.
• For each segment in your assignment, you will receive a packet of segment materials containing the maps, listings, and information sheets that are needed to work your assignment.
• In order to successfully complete your NSDUH cases, you will need to locate your segment, identifying the most efficient route of travel to/from your home and within the segment.
• In order to ensure that we have an accurate sample, it will be necessary for you to check for missed dwelling units. The Newton screening program has steps in place to assist you.

1. Define a group quarters unit.
2. On the Block Listing Map, what does a box with a number inside indicate?
3. What should you do if you find a completely new subdivision in your segment that is not on your map or on the lists?
4. Name three examples of types of homes or structures that are NOT to be included in the sample for the NSDUH.
5. Take some time to become familiar with the Original List of DUs and the Selected DU List.
   1. How many GQUs are in the shelter listed as line 25? (Refer to Group Quarters Listing Form.)
   2. How many selected DUs are on Cambridge Avenue?
   3. What is the street address for line 14? Will you visit that house?
   4. What does the description for the selected DU on line 3 mean? (Refer to Selected DU List.)

This page was last updated on May 16, 2008 .

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