Summary of Findings

Half of all privately owned housing units started in 1976 were built for sale and of these, slightly more than one-tenth were intended for condominium ownership; in effect, one out of twenty units started was intended for condominium ownership. These proportions are unchanged from those of 1975. As shown in Table S-1, condominium ownership can refer to either single family houses or units in multifamily buildings. Under condominium ownership, the owners of the individual housing units are also joint owners of the common areas of the building or community.

A small number of units in buildings with five units or more were sold for cooperative ownership. Under this type of ownership, the occupant of a housing units owns stock in a project as a whole, but does not actually own the unit in which he lives.

Table S-2 shows that approximately 5 percent of the new privately owned housing units started in 1976 were either townhouses or townhouse apartments, unchanged from 1975. The West had a greater number of these than any other region, both in absolute terms and as a proportion of total starts within region.

For purposes of this report, in addition to single family detached houses, the Bureau defines as single family houses those townhouses in groups of two or more which are separated from adjoining units by an unbroken ground-to-roof wall (no common attic or basement) and have their own separate utilities which are not shared with any of the other units. Builders of multifamily structures containing 5 units or more and 3 floors or less were asked to differentiate between townhouse apartments and conventional apartments.

Reliability of the Estimates

The statistics in this supplement are estimates from a sample survey and may differ from the statistics which would have been obtained from a complete census using the same schedules and procedures. An estimate based on a sample survey is subject to both sampling error and nonsampling error. The "accuracy" of a survey result is determined by the joint effect of these errors. Sampling error reflects the fact that only a particular sample was surveyed rather than the entire population. Nonsampling errors can be attributed to many sources: inability to obtain information about all cases in the sample; definitional problems; differences in interpretation of

questions; inability or unwillingness by respondents to provide correct information; and errors made in processing data.

Since "design" and "ownership" characteristics may present more of a conceptual problem to respondents than other statistics in this supplement, the estimates of these characteristics may be subject to slightly higher nonsampling errors. No explicit measures are available for such errors; however, we believe that most of the important operational errors were detected during the review of data for reasonableness and consistency.

The particular sample selected for this survey is one of a large number of similar probability samples that, by chance, might have been selected under the same sample design. Estimates derived from the different samples would differ from each other. The standard error or sampling error of a survey estimate is a measure of the variation among the estimates from all possible samples and thus is a measure of the precision with which an estimate from a particular sample approximates the average results of all possible samples. Estimates of the standard errors have been computed from the sample data. They are presented in the tables in the form of relative standard errors, the standard error divided by the estimated value to which they refer.

The sample estimate and an estimate of its standard error permit us to construct interval estimates with prescribed confidence that the interval includes the average result of all possible samples (for a given sampling rate). For example, Table S-1 shows that 319,000 housing units were started in 1976 for rental purposes. The relative standard error of this estimate is 3 percent. Multiplying 319,000 by .03, we obtain 9,570 as the standard error. This means that we are confident, with two chances out of three of being correct, that the average estimate, from all possible samples, of housing units started in 1976 for rent is between 309,430 and 328,570 units. Doubling the interval gives us limits of 299,860 and 388,140 increasing our confidence of being correct to 19 out of 20 times that the interval contains the average value over all possible samples. We would have almost certain confidence by tripling the interval. The average estimate of housing units started in 1976 for rent may or may not be contained in any one of these computed intervals; but for this particular sample, one can say that the average estimate from all possible samples is included in the constructed interval with a specified confidence: that is, two chances out of three, etc.

DEFINITIONS

A housing start consists of the start of construction of a new housing unit, when located within a new building which is intended primarily as a housekeeping residential building designed for non transient occupancy. Start of construction for private housing units is defined as the beginning of excavation for the foundation of a building; for public housing units it is defined as when the construction contract is awarded. All housing units in a multi-family building are counted as being started when excavation for the building is started. A housing unit is a single room or group of rooms intended for occupancy as separate living quarters by a family, by a group of unrelated persons living together, or by a person living alone. A housekeeping residential building is one consisting primarily of housing units. Housing starts exclude group quarters (such as dormitories and rooming. houses) and transient accommodations (such as transient hotels, motels, and tourist courts) and mobile homes (trailers). Publicly owned housing includes housing units in buildings for which construction contracts were awarded by Federal, State or local governments. Units in structures built by private developers for sale upon completion to local public housing authorities under the U.S. Department of Housing and Urban Development "Turnkey" program are classified as private housing.

The standard census geographic regions are used in the tables of this report. States contained in each region are as follows: Northeast-Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Pennsylvania; North Central-Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas; South-Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Louisiana, Oklahoma, and Texas; West-Montana, Idaho, Wyoming. Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, California, Alaska, and Hawaii.

The distribution of housing starts between units inside and units outside Standard Metropolitan Statistical Areas (SMSA's) is based on the definitions published by the Office of Management and Budget in Standard Metropolitan Statistical Areas. Data for the period beginning January 1976 are based on the 1974 definitions as amended August 1975; data for the period January 1975-December 1975 are based on the 1967 definitions, as amended April 1974; data for the period January 1974-December 1974 are based on the 1967 definitions, as amended November 1973; data for April 1973-December 1973 are based on the 1967 definitions as amended February 1973; data for April 1968-March 1973 are based on 1967 definitions.

HOUSING STARTS COMPILATION

Compilation of the housing starts series depends on four steps. First, an estimate is made of the number of housing units for which building permits have been issued in all 14,000 permit-issuing places each month. Second, a survey is made each month in a sample of permit places. In each place, a sample of building permits is selected each month and an inquiry is made of the owner or the builder to find out whether and when the units covered by the permit have been started. In case the units authorized by permits in a particular month are not started by the end of that month, follow-ups are made in successive months to find out when the units were actually started. From this sample of permits, ratios are calculated, by type of structure, of the number of units started to the number of units covered by permits; separate ratios are calculated for units started each month from permits of that month and of each preceding month. These ratios are then applied to the total number of units authorized (by type of structure) by permits in the corresponding months to provide estimates of the total number of units started each month with permit authorization. Third, having produced an estimate of the number of units started in each month with permit authorization, an upward adjustment of 3.3 percent is next made to the number of one-family homes started to take care of those units started within permit-issuing areas but without permit authorization. (A study spanning a four year period indicated that permits were obtained for all buildings with 2 housing units or more.) The fourth step in estimating total housing starts is to estimate the number of units started in areas where building permit systems do not exist. In a sample of these areas (counties or groups of counties), visits are made to a select group of persons who are presumed most likely to know about local housing activities. A list is obtained from them of all residential buildings they know to have been started within these areas during the preceding month. Next, the information provided by these sources is verified by field visit or by telephone interview with the owners or builders. As the next step, a subsample of small land areas is canvassed intensively by Census employees who look for all units. started since the previous month, identifying those not reported by the sources as well as those reported by them. This canvass provides a basis for estimating the number of units not reported by the local sources. Units not reported by local sources are then added to the number of units reported by these sources, with appropriate weighting, to provide an estimate of total housing starts in areas not covered by building permit systems.

Information on public housing is obtained, for the most part, from the agencies involved, e.g., Department of Housing and Urban Development, Department of Defense, etc.

All privately owned housing units started or authorized in permit-issuing places are treated as nonfarm housing even though a negligible number are located on farm properties. All publicly owned housing units started are treated as nonfarm housing.

STARTS BY TYPE OF STRUCTURE

A total of 14 different sets of starts rates that change from month to month are employed to calculate number of housing units started by type of structure in permit places. Eight sets of starts rates are used for one-family houses: separate sets of rates for metropolitan and nonmetropolitan areas within each of the four regions. For structures with 5 units or more, separate sets of starts rates are used for each of the four regions. Single sets of starts rates are used for all regions for structures with 2 units and for structures with 3-4 units.

Starts by type of structure in nonpermit areas are calculated directly in the estimating procedure described above. Less than 5 percent of the units started in nonpermit areas in 1976 were in buildings with 2 housing units or more.

BUILDING PERMITS

Data on housing units authorized by local building permits relate to the time of issuance rather than to the actual start of construction. They do, however, provide some indication of activity in residential building in advance of the start of actual construction. Although construction is started on most residential buildings in the same month in which the perimit is issued, several months may pass before start of construction.

The 14,000 areas with local building permit systems for which figures are currently given in this report account for a major portion of residential building in the United States. For the country as a whole, approximately 81 percent of the private housing units were constructed in permit-issuing places in 1976.

The monthly series and 1973-1976 annual data reflect the 14,000 places in the United States which were identified in 1972 as having local building permit systems. Annual data for both the 13,000 and 14,000 places are shown for 1971 and 1972. Annual data for 1968 through 1970 reflect the 13,000 places identified in 1967 as having local building permit systems.

Basically, the procedure followed in arriving at the monthly building permit authorization totals involves the cumulating of monthly data from all permit-issuing places that authorized 50 housing units or more (20 or more in some states) in a recent year along with estimates for the less active places based on a stratified probability sample of these places.

A more detailed discussion of the uses and limitations of building permit data is provided in the Census Bureau's monthly report on Building Permits (C40).

MOBILE HOME SHIPMENTS

Statistics on manufacturers' shipments of mobile homes are provided by the Manufactured Housing Institute and include estimates for firms not associated with the MHI.

The total of new housing starts and manufacturers' shipments of mobile homes is shown because an addition to the housing supply is made by mobile homes as well as by the construction of new housing units. Some of the mobile homes shipped by manufacturers, however, as well as some of the new housing units started, are used as seasonal homes and second homes and do not add to the supply of housing units occupied as usual places of residence. Furthermore, some are used for nonresidential purposes. The number of mobile homes or new housing units used in these ways is not now known.

SAMPLING VARIABILITY

The various estimates of private residential housing units started and private housing units authorized by local building permits, which are shown in this publication, are based on samples and may differ from statistics which would have been obtained from a complete census using the same schedules and procedures.

An estimate based on a sample survey is subject to both sampling error and nonsampling error. The accuracy of a survey result is determined by the joint effect of these errors. Sampling error reflects the fact that only a particular sample was surveyed rather than the entire population. Estimates of size of the sampling errors are provided by the standard error of the estimates. Nonsampling errors can be attributed to many sources: inability to obtain information about all cases in the sample; definitional difficulties; differences in interpretation of questions; inability or unwillingness of respondents to provide correct information; and errors made in processing data. No explicit measures of the effects of nonsampling errors are available; however, it is believed that most of the important response and operational errors were detected in the course of reviewing the data for reasonableness and consistency. As derived for this report, the estimated standard errors include part of the effect of nonsampling errors but do not measure any systematic biases in the data.

The particular samples selected for the Housing Starts and Building Permits surveys are each one of a large number of similar probability samples that, by chance, might have been selected under the same specifications. Estimates derived from the different samples would differ from each other. The standard error or sampling error of a survey estimate is a measure of the variation among the estimates from all possible samples and thus is a measure of the precision with which an estimate from a particular sample approximates the average results of all possible samples.

Estimates of the standard errors have been computed from the sample data for selected statistics in this report. They are presented in the form of relative standard errors, the standard error divided by the estimated value to which they refer.