Current Population Survey Design and Methodology - Census Bureau
Current Population Survey Design and Methodology - Census Bureau
Current Population Survey Design and Methodology - Census Bureau
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Table 3–5. Examples of Post-Sampling Operational Code Assignments Within a PSU<br />
BPC number<br />
County Frame Block Index<br />
Sample<br />
designation<br />
Final hit<br />
number<br />
Field<br />
PSU Segment/<br />
suffix<br />
1 1 Unit 1 3 A1 1 1 8999<br />
1 1 Unit 1 4 A2 1 1 8999<br />
1 1 Unit 2 27 A1 2 1 1999<br />
1 2 Unit 2 28 A2 2 2 1999<br />
1 2 Unit 3 51 A1 3 2 2999<br />
1 2 Unit 3 52 A2 3 2 2999<br />
1 1 Group quarters 4 10 A1 4 1 3599<br />
1 1 Group quarters 4 11 A2 4 1 3599<br />
1 1 Area 5 1 A2 5 1 4699<br />
1 1 Area 6 32 A1 6 1 5699<br />
1 1 Area 6 33 A2 6 1 5699<br />
2 3 Unit 7 10 A1 7 3 6999<br />
2 3 Unit 7 11 A2 7 3 6999<br />
2 3 Unit 8 34 A1 8 3 7999<br />
2 3 Unit 8 35 A2 8 3 7999<br />
2 3 Area 9 6 A1 9 3 8699<br />
2 3 Area 10 7 A2 9 3 8699A<br />
1 1 Permit 7 A1 1 1 3001<br />
1 1 Permit 8 A2 1 1 3001<br />
1 2 Permit 45 A1 2 2 4001<br />
1 2 Permit 46 A2 2 2 4001<br />
2 3 Permit 14 A1 3 3 5001<br />
2 3 Permit 15 A2 3 3 5001<br />
THIRD STAGE OF THE SAMPLE DESIGN<br />
The actual USU size in the field can deviate from what is<br />
expected from the computer sampling. Occasionally, the<br />
deviation is large enough to jeopardize the successful<br />
completion of a field representative’s assignment. When<br />
these situations occur, a third stage of selection is conducted<br />
to maintain a manageable field representative<br />
workload. This third stage is called field subsampling.<br />
Field subsampling occurs when a USU consists of more<br />
than 15 sample housing units identified for interview. Usually,<br />
this USU is identified after a listing operation. (See<br />
Chapter 4 for a description of field listing.) The regional<br />
office staff selects a systematic subsample of the USU to<br />
reduce the number of sample housing units to a more<br />
manageable number, from 8 to 15 housing units. To facilitate<br />
the subsampling, an integer take-every (TE) <strong>and</strong> startwith<br />
(SW) are used. An appropriate value of the TE reduces<br />
the USU size to the desired range. For example, if the USU<br />
consists of 16 to 30 housing units, a TE of 2 reduces USU<br />
size to 8 to 15 housing units. The SW is a r<strong>and</strong>omly<br />
selected integer between 1 <strong>and</strong> the TE.<br />
Field subsampling changes the probability of selection for<br />
the housing units in the USU. An appropriate adjustment<br />
to the probability of selection is made by applying a special<br />
weighting factor in the weighting procedure. See ‘‘Special<br />
Weighting Adjustments’’ in Chapter 10 for more on<br />
this procedure.<br />
ROTATION OF THE SAMPLE<br />
The CPS sample rotation scheme is a compromise between<br />
a permanent sample (from which a high response rate<br />
would be difficult to maintain) <strong>and</strong> a completely new<br />
<strong>Current</strong> <strong>Population</strong> <strong>Survey</strong> TP66<br />
U.S. <strong>Bureau</strong> of Labor Statistics <strong>and</strong> U.S. <strong>Census</strong> <strong>Bureau</strong><br />
sample each month (which results in more variable estimates<br />
of change). The CPS sample rotation scheme represents<br />
an attempt to strike a balance in the minimization of<br />
the following:<br />
1. Variance of estimates of month-to-month change:<br />
three-fourths of the sample is the same in consecutive<br />
months.<br />
2. Variance of estimates of year-to-year change: one-half<br />
of the sample is the same in the same month of consecutive<br />
years.<br />
3. Variance of other estimates of change: outgoing<br />
sample is replaced by sample likely to have similar<br />
characteristics.<br />
4. Response burden: eight interviews are dispersed<br />
across 16 months.<br />
The rotation scheme follows a 4-8-4 pattern. A housing<br />
unit or group quarters is interviewed 4 consecutive<br />
months, not in sample for the next 8 months, interviewed<br />
the next 4 months, <strong>and</strong> then retired from sample. The<br />
rotation scheme is designed so outgoing housing units are<br />
replaced by housing units from the same hit string which<br />
have similar characteristics.<br />
The following summarizes the main characteristics (in<br />
addition to the sample overlap described above) of the<br />
CPS rotation scheme:<br />
1. In any single month, one-eighth of the sample housing<br />
units are interviewed for the first time; another eighth<br />
is interviewed for the second time; <strong>and</strong> so on.<br />
<strong>Design</strong> of the <strong>Current</strong> <strong>Population</strong> <strong>Survey</strong> Sample 3–13