APPENDIX A
1995 SURVEY METHODOLOGY

The data on doctoral scientists and engineers contained in this report come from the 1995 Survey of Doctorate Recipients (SDR). The National Research Council (NRC) has conducted the SDR biennially since 1973 for the National Science Foundation (NSF). Additional data on education and demographic information come from the National Research Council’s Doctorate Records File (DRF). The DRF contains data from an ongoing census of research doctorates earned in the United States since 1920. This appendix contains an overview of the survey methodology; a more detailed description is available under separate cover. 1

Sample Design

The sampling frame for the SDR is compiled from the DRF. For the 1995 survey the sampling frame comprised individuals who:

  • had earned a doctoral degree from a U.S. college or university in a science or engineering field;

  • were U.S. citizens or, if non-U.S, citizens, indicated that they had plans to remain in the United States after degree award; and

  • were under 76 years of age.

To develop the frame, graduates who had earned their degrees since 1995 and met the conditions listed above were added to the frame; those who were carried over from 1993 but had attained the age of 76 (or had died) were deleted. A sample of the incoming graduates was drawn and added to the panel sample conveyed from year to year. A maintenance cut was done to keep the sample size roughly the same as it was in 1993. In 1995, the SDR sample size was 49,829.

The basic sample design was a stratified random sample with the goal of proportional sampling across strata. The variables used for stratification were 15 broad fields of degree, 2 genders, and an 8-category “group” variable combining race/ethnicity, handicap status, and citizenship status.

In determining sampling rates the goal was to achieve as much homogeneity as possible while allowing for oversampling of certain small populations (e.g., minority women). In practice, however, the goal of proportional sampling was not consistently achieved. A number of sample size adjustments over the years, in combination with changes to the stratification, led to highly variable sampling rates, sometimes within the same sampling cell. The overall sampling rate was about 1 in 12 (8 percent), applied to a

1  

Brown, Prudence, 1997, Methodological Report of the 1995 Survey of Doctorate Recipients, National Research Council, Washington, DC.



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Doctoral Scientists and Engineers in the United States APPENDIX A 1995 SURVEY METHODOLOGY The data on doctoral scientists and engineers contained in this report come from the 1995 Survey of Doctorate Recipients (SDR). The National Research Council (NRC) has conducted the SDR biennially since 1973 for the National Science Foundation (NSF). Additional data on education and demographic information come from the National Research Council’s Doctorate Records File (DRF). The DRF contains data from an ongoing census of research doctorates earned in the United States since 1920. This appendix contains an overview of the survey methodology; a more detailed description is available under separate cover. 1 Sample Design The sampling frame for the SDR is compiled from the DRF. For the 1995 survey the sampling frame comprised individuals who: had earned a doctoral degree from a U.S. college or university in a science or engineering field; were U.S. citizens or, if non-U.S, citizens, indicated that they had plans to remain in the United States after degree award; and were under 76 years of age. To develop the frame, graduates who had earned their degrees since 1995 and met the conditions listed above were added to the frame; those who were carried over from 1993 but had attained the age of 76 (or had died) were deleted. A sample of the incoming graduates was drawn and added to the panel sample conveyed from year to year. A maintenance cut was done to keep the sample size roughly the same as it was in 1993. In 1995, the SDR sample size was 49,829. The basic sample design was a stratified random sample with the goal of proportional sampling across strata. The variables used for stratification were 15 broad fields of degree, 2 genders, and an 8-category “group” variable combining race/ethnicity, handicap status, and citizenship status. In determining sampling rates the goal was to achieve as much homogeneity as possible while allowing for oversampling of certain small populations (e.g., minority women). In practice, however, the goal of proportional sampling was not consistently achieved. A number of sample size adjustments over the years, in combination with changes to the stratification, led to highly variable sampling rates, sometimes within the same sampling cell. The overall sampling rate was about 1 in 12 (8 percent), applied to a 1   Brown, Prudence, 1997, Methodological Report of the 1995 Survey of Doctorate Recipients, National Research Council, Washington, DC.