DEFINITIONS AND EXPLANATIONS

Except for the instances noted below, the concepts and definitions used in the quarterly surveys are identical with those used in the 1960 Census.

Standard metropolitan statistical area (SMSA).--Except in New England, an SMSA is a county or group of contiguous counties which contains at least one city of 50,000 inhabitants or more, or "twin cities" with a combined population of at least 50,000, the smaller of which must have at least 15,000. In addition to the county, or counties, containing such a city or cities, contiguous counties are included in an SMSA if, according to certain criteria, they are essentially metropolitan in character and are socially and economically integrated with the central city. In New SMSA's consist of towns and cities, England, rather than counties. A more detailed discussion of the criteria used to define SMSA's is given in 1960 Census of Housing, ume I, States and Small Areas.

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The statistics for inside SMSA's and outside SMSA's presented for the first quarters 1966 and 1965 relate to the areas (212) designated SMSA's at the time of the April 1960 Census. Prior to the second quarter 1962, the statistics related to the areas (168) designated SMA's at the time of the 1950 Census. For a list of the 212 SMSA's and individual chapters their constituent parts, refer to the (or Series HC (1) reports) in the 1960 Census of Housing, Volume I, States and Small Areas; or to the 1960 Census of Population, Volume I, Number of Inhabitants. For a list of the 168 areas and their constituent parts, refer to the individual chapters (or bulletins) in the 1950 Census of Housing, Volume I, General Characteristics; or to the 1950 Census of Population, Volume I, Number of Inhabitants, or Volume II, Characteristics of the Population, Part I, United States Summary.

Housing unit. --Beginning with the second quarter 1960, the 1960 Census housing unit concept was used to enumerate separate living quarters. Prior to that time, separate living quarters were enumerated according to the 1950 dwelling unit definition. The major difference between the two is not in content but in sharpening of the criteria by which separate units are identified. It is expected that the housing unit concept will yield better coverage of both occupied and vacant living quarters than the dwelling unit concept. Although no statistical measure of the effect of the change is available at this time, it is believed to be too small to affect the vacancy rates.

A group of rooms, or a single room is regarded as a housing unit when it is occupied as separate living quarters, that is, when the occupants do not live and eat with any other persons in the structure, and when there is either (1) direct access from the outside or through a common hall, or (2) a kitchen or cooking equipment for the exclusive use of the occupants.

Vacant living quarters which are intended for occupancy as separate living quarters and meet the physical criteria defined above are separate housing units. Since it is customary in some localities for occupants to furnish their own cooking equipment, vacant units without a kitchen or cooking equipment are considered to have such equipment if the last occupants had cooking equipment.

Living quarters of the following types are excluded from the housing unit inventory: dormitories, bunkhouses, and barracks; quarters in predominantly transient hotels, motels, and the like, except those occupied by persons who consider the hotel their usual place of residence; quarters

Dwelling unit, 1950.--The 1950 dwelling unit was defined as follows: A group of rooms occupied as separate living quarters was a dwelling unit if it had separate cooking equipment or if it constituted the only living quarters in the structure. Each apartment in a regular apartment house was a dwelling unit even though it may not have had separate cooking equipment. Apartments in residential hotels were dwelling units if they had separate cooking equipment or consisted of two or more rooms.

Vacant quarters which were intended for occupancy as separate living quarters and met the physical criteria defined above were separate dwelling units. Vacant units were considered as having cooking equipment if they were equipped with such equipment or if the last occupants had cooking equipment.

In general, living quarters of the types excluded from the housing unit inventory were excluded from the dwelling unit inventory.

Occupied housing units.--A housing unit is occupied if a person or group of persons was living in it at the time of enumeration or if the occupants were only temporarily absent, as for example, on vacation. The persons living in the unit must consider it their usual place of residence or have no usual place of residence elsewhere. The count of occupied housing units is the same as the count of households.

Units occupied by persons with usual residence elsewhere.--A housing unit which is occupied temporarily by persons who usually live elsewhere is enumerated as a vacant unit provided the usual place of residence is held for the household and is not offered for rent or for sale. For example, a beach cottage occupied at the time of enumeration by a family which has a usual place of residence in the city is included in the count of vacant units. Their house in the city would be reported "occupied" and would be included in the count of occupied units since the occupants are only temporarily absent.

Units occupied by persons with usual residence elsewhere are included with seasonal units or with year-round vacant units as dilapidated, or not dilapidated but held off the market, as the case may be.

Vacant housing units.--A housing unit (furnished or unfurnished) is vacant if no persons were living in it at the time of enumeration, except when its occupants were only temporarily absent. Dilapidated vacant units were included if they were intended for occupancy as living quarters; however, if the vacant unit was unfit for use and beyond repair so that it was no longer considered living quarters, it was excluded from the inventory. Vacant

units to be demolished were excluded if unfit or if there was positive evidence, such as a sign or mark on the house or in the block, that the unit was to be torn down. New

units not yet occupied were enumerated as vacant housing units if construction had proceeded to the point that all the exterior windows and doors were installed and final usable floors were in place; otherwise, potential units under construction were not included. Unoccupied units held off the market for various reasons and units recently rented or sold but not yet occupied are considered vacant.

Vacant sleeping rooms in lodginghouses, transient accommodations, barracks, and other quarters not defined as housing units are not included in the statistics in this report. (See section on "Housing unit.")

Year-round vacant units.--Year-round units are those intended for occupancy at any time of the year, even though they may not be in use the year round. In resort areas, a housing unit which is usually occupied on a year-round basis was considered a year-round unit. On the other hand, a housing unit located in the closely built-up area of a nonresort city was considered a "year round" unit even though it may be occupied only part of the year. As indicated above, year-round units temporarily occupied by persons with usual residence elsewhere are included with year-round vacant units.

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Seasonal vacant units.--Seasonal housing units those intended for occupancy during only a season year and are found primarily in resort areas. In farm areas, housing units used for only a portion of the year to house migratory workers employed during the crop season are classified as seasonal.

Seasonal units comprise unoccupied seasonal units and seasonal units temporarily occupied by persons with usual residence elsewhere. Units in resort areas occupied by persons who considered the unit their usual place of residence or had no other place of residence are classified as occupied. (See also section on "Occupied housing units.")

Available vacant units.--The categories "available for rent" and "available for sale only" provide a measure of vacant housing units which are on the market for yearround occupancy, are in either sound or deteriorating condition, and are being offered for rent or for sale. These categories are comparable with the 1950 categories "Nonseasonal not dilapidated, for rent" and "Nonseasonal not dilapidated, for sale only."

To describe the rental and sale market, the measure of units available for rent is expressed as a percentage of the total rental inventory and the measure of units available for sale is expressed as a percentage of the total homeowner inventory. In the analysis of the total inventory and total vacant units, percentages are based on total housing units.

Vacant units available for rent.--This group consists of available vacant units offered for rent and those offered "for rent or sale."

Vacant units available for sale only.--This group is limited to units for sale only; it excludes units "for rent or sale." If a unit was located in a multi-unit structure which was for sale as an entire structure, and if the unit was not for rent, it was reported as "held off market." However, if the individual unit was intended to be occupied by the new owner it was reported as for sale.

Vacant units rented or sold.--This group consists of year-round vacant units in sound or deteriorating condition

Vacant units held off the market. -- Included in this category are year-round units in sound or deteriorating condition which were vacant for reasons other than those mentioned above: for example, held for occupancy of a caretaker, janitor, and the like; held for settlement of estate; held for personal reasons of the owner; and temporarily occupied by persons who have a usual place of residence elsewhere. In the 1950 statistics, such units are shown in combination with year-round not dilapidated vacant units, rented or sold, as "nonseasonal not dilapidated,

not for rent or sale" units.

Rental vacancy rate.--The percentage relationship of the vacant units available for rent to the total rental inventory is termed the rental vacancy rate. It is computed by dividing the number of vacant units available for rent by the total rental units. The total rental units consists of the renter-occupied units, vacant units rented but not yet occupied at the time of enumeration, and the vacant units available for rent. Vacant units that are dilapidated, seasonal, or held off the market are excluded.

Homeowner vacancy rate.--The percentage relationship between the vacant units available for sale and the total homeowner inventory is termed the homeowner vacancy rate. It is computed by dividing the number of vacant units available for sale by the total homeowner units. The total homeowner units consists of the owner-occupied units, vacant units sold and awaiting occupancy, and the vacant units available for sale. Vacant units that are dilapidated, seasonal, or held off the market are excluded.

Tenure.--A unit is owner-occupied if the Owner or co-owner lives in the unit, even if it is mortgaged or not fully paid for. All other occupied units are classified as "renter occupied whether or not cash rent is paid. Thus, units occupied in exchange for services rendered and units provided without payment of cash rent are "renter occupied."

Condition of housing unit. --The structural condition of a housing unit is considered one of the measures of the quality of housing. Beginning the first quarter 1961, the condition of vacant housing units was measured according to the concept used in the 1960 Census. Three categories were used: Sound, deteriorating, and dilapidated. In preceding quarters and in 1950, two categories were used: not dilapidated or dilapidated. The category "sound or deteriorating" is assumed to be equivalent to the category

"not dilapidated."

Sound housing has no defects, or only slight defects which are normally corrected during the course of regular maintenance. Examples of slight defects include: lack of paint; slight damage to porch or steps; small cracks in walls, plaster, or chimney; broken gutters or downspouts; slight wear on floors or doorsills.

Deteriorating housing needs more repair than would be provided in the course of regular maintenance. It has one or more defects of an intermediate nature that must be corrected if the unit is to continue to provide safe and adequate shelter. Examples of such defects include: shaky or unsafe porch or steps; holes, open cracks or missing

materials over a small area of the floors,

walls or roof; rotted window sills or frames; deep wear on floors or doorsills; broken or loose stair treads or missing balusters. Such defects are signs of neglect which lead to serious structural damage if not corrected.

Dilapidated housing does not provide safe and adequate shelter. It has one or more critical defects; or has a combination of intermediate defects in sufficient number to require extensive repair or rebuilding; or is of inadequate original construction. Critical defects are those which indicate continued neglect and serious damage to the structure. Examples of critical defects include: holes, open cracks or missing materials over a large area of the floors, walls, roof, or other parts of the structure; sagging floors, walls, or roof; damage by storm or fire. Inadequate original construction includes structures built of makeshift materials and inadequately converted cellars, sheds, or garages not originally intended as living quarters.

The enumerator determined the condition of the housing unit on the basis of his own observation. He was instructed to appraise the condition of units uniformly, regardless of the neighborhood. The enumerator was provided with detailed written instructions and with pictures illustrating the concepts "sound," "deteriorating," and "dilapidated."

Although the enumerator was provided with detailed oral and written instructions and with visual aids, it was not possible to eliminate completely the element of judgment in the enumeration of this item. It is possible that some enumerators obtained too large or too small a count of dilapidated units. However, with the large number of involved, it is likely that such deviations tend to be offsetting.

enumerators

Number of rooms. --All rooms which are to be used, or are suitable for use, as living quarters were counted in determining the number of rooms in the housing unit. Included are kitchens, bedrooms, dining rooms, living rooms, and permanently enclosed sunporches of substantial size; and finished basement or attic rooms, recreation rooms, or other rooms suitable for use as living quarters. A kitchenette or half-room which is partitioned off from floor to ceiling was counted as a separate room, but a combined kitchenette and dinette separated only by shelves or cabinets was counted as only one room. Not counted as rooms were bathrooms, strip or pullman kitchens, halls or foyers, alcoves, pantries, laundries, closets or storage space, and unfinished basement or attic rooms not suitable for living quarters.

The median number of rooms is the theoretical value which divides the housing units equally, one-half having more rooms and one-half having fewer rooms than the median. In the computation of the median, a continuous distribution was assumed. For example, when the median was in the 3-room group, the lower and upper limits were assumed to be 2.5 and 3.5, respectively. Tenths were used in the computation of the median to permit comparisons.

Number of bedrooms.--Only rooms intended primarily to be slept in were counted as bedrooms. A bed-living room or a den intended primarily for purposes other than sleeping was not counted as a bedroom. A 1-room apartment, therefore, was reported as having no bedroom. Also, space which could be made into bedrooms (the upper floor of a 1-story house, for example) was not counted as a bedroom unless it was finished off and suitable for use as living quarters.

Number of housing units in structure.--A structure either stands by itself or has vertical walls dividing it from all other structures. The count of housing units in a structure is the total number of units in the structure, including both occupied and vacant units. A structure may be detached, attached, or semi detached. A detached structure has open space on all four sides; an attached structure is one of a row of three or more adjoining structures, or is a structure attached to a nonresidential structure; while a semi detached structure is one of two adjoining residential structures, each with open space on the remaining three sides. In apartment developments, each building with open space on all sides is considered a separate structure.

The statistics reflect the number of vacant housing units classified by the number of housing units in the structure in which they are located, rather than the number of residential structures that contain vacant units.

In the quarterly surveys, data were obtained on the number of housing units in the structure, regardless of the type of structure (detached, attached, or semi detached) in which the unit was located.

Year structure built.--"Year built" refers to the date the original construction of the structure was completed, not to any later remodeling, addition, or conversion. The figures on the number of units built during a given period relate to the number of units in existence at the time of enumeration. The figures reflect the number of units constructed during a given period plus the number created by conversions in structures originally built during that period, minus the number lost in structures built during the period. Losses occur through demolition, fire, flood, disaster; change to nonresidential use; or merger to fewer housing units.

Data on year built are more susceptible to errors of response and nonreporting than data on many of the other items. In most cases, the information was given according to memory or estimates of the occupants of the structure of other persons who had lived in the neighborhood a long time.

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Duration of vacancy.--The length of time a housing unit was vacant was computed from the day the unit became vacant until the day of enumeration. It should be noted a unit remains in a particular

that the time period is not the total time unoccupied nor the time a unit has been vacancy status, but it is the duration of vacancy up to the day of enumeration. For newly constructed units, it represents the time period since the date when the unit was considered a vacancy, that is, when construction had reached the point that all exterior windows and doors were installed and final usable floors were in place.

The time intervals used in the tables represent full months, calculated from a date in the month to the same date the following months. For example, if the unit became vacant on Jan. 29 and was still vacant on the day of enumeration, March 20, the time reported would be 1 up to 2 months, meaning that the unit had been vacant for more than one month but less than two months. Or if the unit became vacant on Feb. 25 and was still vacant on March 20, the time reported would be less than 1 month."

Plumbing facilities. --Housing units with all facilities" consist of those which have: both a flush toilet and a bathtub or shower inside the structure for the exclusive use of the intended occupants, and hot running water.

Monthly rent.--The monthly rent is the amount asked for the unit at the time of enumeration, regardless of whether it is to include furniture, heating fuel, electricity, cooking fuel, water, or other services. If the amount of rent were to vary during the year, the rent reported was the monthly amount asked at the time of enumeration. As in the 1960 Census, the statistics in this report are for all vacant rental units in urban areas and those in rural areas which are located on places of less than 10 acres; thus rural vacancies on places of 10 acres or more are excluded. The statistics in the reports for 1960 or earlier exclude rental vacancies in rural areas which were classified as farm by the 1950 definition (the classification depending on the reply to the question "Is this house on a farm or ranch?"). Data for such units are excluded because of the difficulty of separating the rental for the housing unit from the rental for the land.

The median monthly rent is the rent which divides the series into two equal parts, one-half of the units with rents higher than the median and the other half with rents lower than the median. In the computation of the median, a continuous distribution was assumed; and the limits of the class intervals were assumed to stand at the midpoints of the 1-dollar interval between the end of one of the rent groups and the beginning of the next. For example, the limits of the interval designated $30 to $39 assumed to be $29.50 and $39.50.

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Inclusion of utilities in rent.--The utilities included in the inquiry were heat, light, cooking fuel, and water. The statistics reflect whether all or not all of these utilities are provided for in the amount of rent asked at the time of enumeration, not what could be provided for more or less rent. Data on the inclusion of utilities are limited to the same units as those for which rent is reported.

Sale price of 1-housing unit structures.--The sale price is the amount asked for the property, including the structure and its land. Statistics on sale price for this report are limited to units in 1-housing unit structures, without business, and with only one housing unit included in the property. As in the 1960 Census, the statistics in this report are for all vacant homeowner units in urban areas and those in rural areas which are located on places of less than 10 acres; thus rural vacancies on places of 10 acres or more are excluded. The statistics in the reports for 1960 or earlier exclude home owner vacancies in

rural areas which were classified as farm by the 1950 definition (the classification depending on the reply to the question "Is this house on a farm or ranch?"). Data for such units are excluded because they would reflect varying amounts for land, business uses, or for more than one housing unit on the property.

The median sale price is the amount which divides the series into two equal parts, one-half of the units with prices higher than the median and the other half with prices lower than the median. The median was computed on the basis of more detailed tabulation groups than are shown in the tables and was rounded to the nearest hundred dollars.

Urban-rural residence. --The territory classified as urban is the same as that in the 1960 Census. Urban housing comprises all units in (a) places of 2,500 inhabitants or more incorporated as cities, boroughs, villages, and towns (except towns in New England, New York, and Wisconsin); (b) the densely settled urban fringe, whether incorporated or unincorporated, of urbanized areas; (c) towns in New England and townships in New Jersey and Pennsylvania which contain no incorporated municipalities as subdivisions and have either 25,000 inhabitants or more or a population of 2,500 to 25,000 and a density of 1,500 persons or more per square mile; (d) counties in States other than the New England States, New Jersey, and Pennsylvania that have no incorporated municipalities within their boundaries and have a density of 1,500 persons or more per square mile; and (e) unincorporated places of 2,500 inhabitants or more. The remaining units are classified as rural.

SOURCE AND RELIABILITY OF DATA

Source of data. --The quarterly estimates presented in this report are based on data obtained in connection with the monthly population sample survey of the Bureau of the Census.

The statistics for the first quarter 1966 are averages for the three months, Jan., Feb., and March. Beginning with the second quarter 1960, separate living quarters were enumerated according to the 1960 Census housing unit definition. For the preceding periods, living quarters were enumerated according to the 1950 definition of dwelling unit. The result of the change in definition is believed to be too small to affect the vacancy rates.

The sample is comprised of 701 counties and independent cities with coverage in each of the 50 States and the District of Columbia. Representation from Alaska and Hawaii was included in the sample, beginning January 1960.

A total of approximately 40,000 housing units and other living quarters were designated for each month's sample. Of this total, about 35,000 were occupied housing units; about 3,500 were vacant housing units; and the remainder were units which, at the time of enumeration, had been converted to commercial use, had been demolished, etc., or were not living quarters within the scope of the survey. Detailed information was obtained for each vacant unit in the sample, beginning with the second quarter 1955.

The data for 1960 are based on the returns of the 1960 Census of Housing and represent the results of a complete enumeration.

Reliability of the estimates.--Since the quarterly statistics presented in this report are based on a sample, they are subject to sampling variability and may be expected to differ from results that would have been obtained from a complete count in which identical enumeration techniques were employed. The standard error is a measure of sampling variability. The chances are about 68 out of 100 that the difference due to sampling variability between an estimate and the figure that would have been obtained from a complete enumeration is less than the standard error. The chances are about 95 out of 100 that the difference is less than twice the standard error and about 99 out of 100 that it is less than 2 times the standard error.

The annual average rates are subject to a smaller sampling variability than the quarterly rates. The variability

for the annual average rate can be approximated by taking one-half of the standard error of the rate in

table A.

for the

Comparison of characteristics of vacancies first quarter 1966 with those for previous quarters (Series H-111, Nos. 1 to 43) reveals that many of the differences are small. A small difference, particularly when it is based on a small subclass of vacant housing units, should be interpreted with care. As can be seen from table A, the sampling variability in such cases may be large relative to the difference.

In addition to sampling variability, the data are subject to errors of response and biases due to nonreporting. Factors affecting accuracy of reporting are the respondent's knowledge of the facts and the enumerator's ability to obtain accurate information and classify the unit with respect to such items as condition, seasonal status, number of rooms, rent, sale price, and the like. The 1960 data also are subject to such possible biases and errors of response.