Using the American Community Survey for the National Science Foundation's Science and Engineering Workforce Statistics Programs (2008) / Chapter Skim
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6 Using ACS for the NSCG Sample Frame
6 Using ACS for the NSCG Sample Frame
Pages 50-67
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From page 50... ...
REQUIREMENTS AND CONSTRAINTS Requirements In adopting the ACS as the NSCG sampling frame, some aspects of the NSCG sample design, such as weighting of women, minorities, and other population groups, may not change much, but other aspects may be markedly affected by the ACS design. As noted above, the ACS is a continuous monthly sample in contrast to the long form, which used point-intime sampling on Census Day (April 1)
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From page 51... ...
surveys raises several technical issues. The continuous nature of the ACS poses opportunities for frequent updating of the NSCG sample frame, while the limited size of 1 year's ACS sample (relative to the long-form sample)
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From page 52... ...
Cohen of NSF identified some possible drawbacks to using the ACS as a sample frame associated with the need to accumulate a sufficiently large sample to meet specific objectives. The ACS sample over one annual cycle does not capture enough of rare populations for NSCG needs.
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From page 53... ...
may contain enough cases to equal or surpass the size of past NSCG postcensal samples for some populations, but it is unlikely to have enough sample to equal the previous NSCG cell size for the more rare populations (such as minority groups)
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From page 54... ...
A full calendar year (or years) of ACS data needs to be available sufficiently in advance of the NSCG reference date to allow the Census Bureau time to clean and weight the ACS data as well as to allow for sufficient time to select and prepare the NSCG sample for the field.
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From page 55... ...
With an October reference date and a sample based on ACS monthly samples for the previous calendar year, some contact data would be less than 12 months old and none would be older than 22 months. (If 2 years of the ACS sample are used, only the oldest data would be similar in age to the long-form data.)
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From page 56... ...
A shorter time period between the frame and NSCG data collection reduces the likelihood of changes in eligibility status between the two dates, such as moving abroad or earning another degree, and should improve the ability to locate individuals for participation. With a shorter time gap for all or most of the sample between the ACS frame data and the NCSG reference date, a smaller fraction of the NSCG sample cases will have moved from where they were living at the time of the ACS in comparison with the long form frame.
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From page 57... ...
NSF now has to obtain a large increase in resources just after the decennial census to cover sample design costs and the cost of the large screening sample needed to identify the S&E population. THE ACS AS A SAMPLE FRAME The NSCG has evolved over the years into a two-tiered program: a baseline postcensal NSCG followed by subsequent panel follow-up surveys.
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From page 58... ...
As the use of the ACS as a sampling frame matures, NSF and the Census Bureau may wish to consider how ACS paradata could be used to improve S&E workforce data collection and analysis. Even without a change in survey content, the use of the ACS opens the possibility of changing the design of the sample frame for the NSCG in some exciting ways.
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From page 59... ...
On the negative side, it retains the serious cost disadvantages of option 1, and, as an operational drawback, it requires continuous access to the ACS as a sampling frame. Conclusion: The disadvantages of the selective updating design outweigh the potential advantages.
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From page 60... ...
It would maintain the currency of the NSCG sample, permit oversampling of emerging or special interest populations during the decade, prevent discontinuities in the estimates, support trend analysis, and smooth out the NSF budget cycle. A serious disadvantage of this approach is that it would likely require continuous access to the entire ACS sample for all years to derive the desired sample sizes for rare populations.
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From page 61... ...
With three survey cycles per decade, the NSCG has experienced declining response rates as each decade progressed, as well as increasing refusal rates. The rotating sample approach would offer virtually all of the advantages associated with continuous sample updating, plus some additional advantages.
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From page 62... ...
Although the rotating panels maintain the capacity to do longitudinal analysis as each panel will have data collected for a specific number of years, the longitudinal data will not be available for the full sample for all time periods. Conclusion: The rotating sample approach is the most promising of all the NSCG design options and a biennial survey cycle with four or five rotating panels is the most efficient and cost-effective use of the ACS as a sampling frame.
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From page 63... ...
interest. Continuous sample Drawing a fresh Maintains the currency Requires continuous Not an efficient sample updating sample from the of the NSCG sample, access to the ACS design and would limit ACS for each cycle permits oversampling sample for all years use of the ACS for drawing of the NSCG, at least of special interest and may not be cost samples for other surveys.
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From page 64... ...
Conclusion: A hybrid approach using a rotating design for rare pop ulations would have the drawback of not keeping time-in-sample constant across subpopulations and thus might lead to differential levels of nonsampling bias across subpopulations. Recommendation 6.2: If the National Science Foundation wishes to consider continuation of the National Survey of College Graduates with the sample drawn from the American Community Survey, the agency should use a rotating panel design.
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From page 65... ...
There is precedence for the use of unswapped data as the Census Bureau allowed use of unswapped data from the 2000 Decennial Census long form for sampling for the 2003 NSCG. Recommendation 6.4: The Census Bureau should use unswapped American Community Survey data (with sample weights)
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From page 66... ...
ACCESS TO THE ACS SAMPLE FRAME The recommended option of a rotating panel design for the NSCG does not come without risk. Although this design would eliminate periodic demands for a very large sample from the ACS because the entire sample will not be redrawn every cycle, it would require several draws during the decade in contrast to just one at the beginning of the decade.
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From page 67... ...
Other procedures to enable the NSCG sample draw while preserving sample for other surveys may well be developed with additional research. Recommendation 6.6: The National Science Foundation and the Census Bureau should sponsor a research program to explore means of permitting a sample draw from the American Community Survey for a rotation panel for the National Survey of College Graduates while preserving American Community Survey sample units for other surveys.
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