Current Population Survey Design and Methodology - Census Bureau

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