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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences (2011)
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. "Appendix E: Demographic Projections of the Research Workforce in the Biomedical, Clinical, and Behavioral Sciences, 2006-2016 (Using the System Dynamics Simulation Methodology)." Research Training in the Biomedical, Behavioral, and Clinical Research Sciences. Washington, DC: The National Academies Press, 2011.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences

Appendix E
Demographic Projections of the Research Workforce in the Biomedical, Clinical, and Behavioral Sciences, 2006-2016 (Using the System Dynamics Simulation Methodology)

OVERVIEW

Appendix D provides demographic projections of the research workforce in the biomedical, clinical, and behavioral sciences for the years 2006-2016 using a traditional statistical (actuarial) approach. This appendix provides additional demographic projections for the same workforces using an alternative approach called system dynamics that is based on the “structure” of the system (i.e., the interconnections among the various entities or parts of the system). In this case, the system under study is the scientific research workforce.

For each of the biomedical, clinical, and behavioral sciences workforces, projections will be shown for the total population along with the populations in the following four (4) demographic categories:

  1. U.S.-trained males

  2. U.S.-trained females

  3. Foreign-trained males

  4. Foreign-trained females

In each projection, the beginning population values are the actual values for 2006, the latest published set of data points. For each of the three major workforces (i.e., biological, clinical, and behavioral sciences), three (3) scenarios will be considered.

  1. Scenario 1 (Moderate Risk): Use 50 percent of the value of the specified annual growth rate for each subgroup of the workforce. This is rated moderate risk because it is the most likely scenario and has the workforce projections that are most expected.

  2. Scenario 2 (High Risk): Use 75 percent of the value of the specified annual growth rate for each subgroup of the workforce. This is rated high risk because it produces very large workforces over the 10-year simulation.

  3. Scenario 3 (Low Risk): Use Ph.D. student growth rates in a “pipeline” model into the workforce. This is rated low risk because it is the most conservative set of projections for the workforces.

Figure E-1 shows the projections for the three major workforces for Scenario 1, the most likely scenario.

SUMMARY PROJECTIONS FOR ALL THREE SCENARIOS

Figures E-2 through E-4 show the projections for each of the three major workforces for each of the three scenarios in line-graph form. Tables E-1 through E-3 then show the projections for each of the three major workforces for each of the three scenarios in table form.

DEMOGRAPHIC DETAILS FOR SCENARIO 1 (MODERATE RISK)

Figure E-5 shows the projections for each of the four demographic groups for the biomedical sciences workforce for Scenario 1 in bar-graph form, and Table E-4 shows the same projections in table form.

Figure E-6 shows the projections for each of the four demographic groups for the behavioral sciences workforce for Scenario 1 in bar-graph form, and Table E-5 shows the same projections in table form.

Figure E-7 shows the projections for each of the four demographic groups for the clinical sciences workforce for Scenario 1 in bar-graph form, and Table E-6 shows the same projections in table form.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Appendix E Demographic Projections of the Research Workforce in the Biomedical, Clinical, and Behavioral Sciences, 2006-2016 (Using the System Dynamics Simulation Methodology) OVERVIEW Appendix D provides demographic projections of the research workforce in the biomedical, clinical, and behavioral sciences for the years 2006-2016 using a traditional statistical (actuarial) approach. This appendix provides additional demographic projections for the same workforces using an alternative approach called system dynamics that is based on the “structure” of the system (i.e., the interconnections among the various entities or parts of the system). In this case, the system under study is the scientific research workforce. For each of the biomedical, clinical, and behavioral sciences workforces, projections will be shown for the total population along with the populations in the following four (4) demographic categories: U.S.-trained males U.S.-trained females Foreign-trained males Foreign-trained females In each projection, the beginning population values are the actual values for 2006, the latest published set of data points. For each of the three major workforces (i.e., biological, clinical, and behavioral sciences), three (3) scenarios will be considered. Scenario 1 (Moderate Risk): Use 50 percent of the value of the specified annual growth rate for each subgroup of the workforce. This is rated moderate risk because it is the most likely scenario and has the workforce projections that are most expected. Scenario 2 (High Risk): Use 75 percent of the value of the specified annual growth rate for each subgroup of the workforce. This is rated high risk because it produces very large workforces over the 10-year simulation. Scenario 3 (Low Risk): Use Ph.D. student growth rates in a “pipeline” model into the workforce. This is rated low risk because it is the most conservative set of projections for the workforces. Figure E-1 shows the projections for the three major workforces for Scenario 1, the most likely scenario. SUMMARY PROJECTIONS FOR ALL THREE SCENARIOS Figures E-2 through E-4 show the projections for each of the three major workforces for each of the three scenarios in line-graph form. Tables E-1 through E-3 then show the projections for each of the three major workforces for each of the three scenarios in table form. DEMOGRAPHIC DETAILS FOR SCENARIO 1 (MODERATE RISK) Figure E-5 shows the projections for each of the four demographic groups for the biomedical sciences workforce for Scenario 1 in bar-graph form, and Table E-4 shows the same projections in table form. Figure E-6 shows the projections for each of the four demographic groups for the behavioral sciences workforce for Scenario 1 in bar-graph form, and Table E-5 shows the same projections in table form. Figure E-7 shows the projections for each of the four demographic groups for the clinical sciences workforce for Scenario 1 in bar-graph form, and Table E-6 shows the same projections in table form.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-1 Total biomedical, behavioral, and clinical sciences workforces, 2006-2016, scenario 1. SOURCE: NRC analysis. FIGURE E-2 Total biomedical sciences workforce, 2006-2016. SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-3 Total behavioral sciences workforce, 2006-2016. SOURCE: NRC analysis. FIGURE E-4 Total clinical sciences workforce, 2006-2016. SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences TABLE E-1 Biomedical Sciences Workforce Projections for All Scenarios   BIOMEDICAL   Scenario 1 Scenario 2 Scenario 3 2006 159,853 159,853 159,853 2007 162,950 164,598 162,926 2008 166,423 170,244 166,296 2009 170,339 177,046 169,995 2010 174,782 185,354 174,063 2011 179,854 195,662 178,543 2012 185,684 208,677 183,489 2013 192,437 225,425 188,959 2014 200,321 247,417 195,024 2015 209,607 276,908 201,764 2016 220,642 317,302 209,274 SOURCE: NRC analysis. TABLE E-2 Behavioral Sciences Workforce Projections for All Scenarios   BEHAVIORAL   Scenario 1 Scenario 2 Scenario 3 2006 124,292 124,292 124,292 2007 127,049 128,501 125,660 2008 130,079 133,351 127,051 2009 133,414 138,958 128,465 2010 137,091 145,459 129,906 2011 141,149 153,018 131,373 2012 145,634 161,832 132,871 2013 150,599 172,137 134,399 2014 156,100 184,214 135,962 2015 162,203 198,404 137,561 2016 168,983 215,115 139,198 SOURCE: NRC analysis. TABLE E-3 Clinical Sciences Workforce Projections for All Scenarios   CLINICAL   Scenario 1 Scenario 2 Scenario 3 2006 35,320 35,320 35,320 2007 36,327 36,859 36,291 2008 37,441 38,654 37,319 2009 38,680 40,763 38,408 2010 40,061 43,256 39,562 2011 41,605 46,221 40,785 2012 43,335 49,765 42,082 2013 45,279 54,024 43,456 2014 47,470 59,162 44,913 2015 49,943 65,388 46,458 2016 52,743 72,957 48,097 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-5 Breakout of biomedical sciences workforce, 2006-2016, scenario 1. SOURCE: NRC analysis. TABLE E-4 Breakout of Biomedical Sciences Workforce, 2006-2016, Scenario 1   BIOMEDICAL - SCENARIO 1 DETAILS   US Male US Female Foreign Male Foreign Female 2006 80,268 45,828 23,636 10,121 2007 81,782 46,989 23,943 10,236 2008 83,502 48,218 24,337 10,366 2009 85,455 49,522 24,848 10,515 2010 87,675 50,906 25,517 10,684 2011 90,198 52,378 26,401 10,876 2012 93,066 53,946 27,577 11,095 2013 96,327 55,618 29,147 11,345 2014 100,034 57,403 31,254 11,629 2015 104,250 59,312 34,091 11,953 2016 109,044 61,356 37,919 12,322 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-6 Breakout of behavioral sciences workforce, 2006-2016, scenario 1. SOURCE: NRC analysis. TABLE E-5 Breakout of Behavioral Sciences Workforce, 2006-2016, Scenario 1   BEHAVIORAL - SCENARIO 1 DETAILS   US Male US Female Foreign Male Foreign Female 2006 57,593 62,758 1,457 2,484 2007 58,495 64,335 1,464 2,755 2008 59,471 66,066 1,471 3,071 2009 60,525 67,971 1,478 3,440 2010 61,665 70,069 1,485 3,871 2011 62,897 72,384 1,492 4,375 2012 64,230 74,941 1,499 4,964 2013 65,671 77,770 1,507 5,652 2014 67,229 80,901 1,514 6,457 2015 68,914 84,371 1,521 7,398 2016 70,736 88,221 1,529 8,498 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-7 Breakout of clinical sciences workforce, 2006-2016, scenario 1. SOURCE: NRC analysis. TABLE E-6 Breakout of Clinical Sciences Workforce, 2006-2016, Scenario 1   CLINICAL - SCENARIO 1 DETAILS   US Male US Female Foreign Male Foreign Female 2006 9,457 14,706 6,359 4,798 2007 9,737 15,368 6,378 4,844 2008 10,055 16,096 6,398 4,893 2009 10,417 16,902 6,417 4,944 2010 10,829 17,797 6,436 4,998 2011 11,299 18,794 6,456 5,056 2012 11,835 19,909 6,475 5,116 2013 12,446 21,159 6,495 5,179 2014 13,143 22,566 6,515 5,246 2015 13,938 24,154 6,534 5,317 2016 14,846 25,952 6,554 5,391 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences DEMOGRAPHIC DETAILS FOR SCENARIO 2 (HIGH RISK) Figure E-8 shows the projections for each of the four demographic groups for the biomedical sciences workforce for Scenario 2 in bar-graph form, and Table E-7 shows the same projections in table form. FIGURE E-8 Breakout of biomedical sciences workforce, 2006-2016, scenario 2. SOURCE: NRC analysis. TABLE E-7 Breakout of Biomedical Sciences Workforce, 2006-2016, Scenario 2   BIOMEDICAL - SCENARIO 2 DETAILS   US Male US Female Foreign Male Foreign Female 2006 80,268 45,828 23,636 10,121 2007 82,594 47,588 24,119 10,297 2008 85,406 49,507 24,820 10,511 2009 88,808 51,605 25,863 10,770 2010 92,923 53,908 27,439 11,084 2011 97,903 56,441 29,852 11,466 2012 103,933 59,238 33,578 11,929 2013 111,235 62,333 39,367 12,490 2014 120,078 65,769 48,398 13,171 2015 130,791 69,591 62,528 13,998 2016 143,771 73,855 84,676 15,000 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Figure E-9 shows the projections for each of the four demographic groups for the behavioral sciences workforce for Scenario 2 in bar-graph form, and Table E-8 shows the same projections in table form. FIGURE E-9 Breakout of behavioral sciences workforce, 2006-2016, scenario 2. SOURCE: NRC analysis. TABLE E-8 Breakout of Behavioral Sciences Workforce, 2006-2016, Scenario 2   BEHAVIORAL - SCENARIO 2 DETAILS   US Male US Female Foreign Male Foreign Female 2006 57,593 62,758 1,457 2,484 2007 58,966 65,165 1,467 2,902 2008 60,509 67,936 1,478 3,429 2009 62,242 71,135 1,489 4,092 2010 64,190 74,842 1,499 4,928 2011 66,378 79,148 1,510 5,982 2012 68,838 84,162 1,521 7,311 2013 71,602 90,014 1,532 8,988 2014 74,710 96,856 1,544 11,105 2015 78,204 104,868 1,555 13,778 2016 82,132 114,264 1,567 17,154 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Figure E-10 shows the projections for each of the four demographic groups for the clinical sciences workforce for Scenario 2 in bar-graph form, and Table E-9 shows the same projections in table form. FIGURE E-10 Breakout of clinical sciences workforce, 2006-2016, scenario 2. SOURCE: NRC analysis. TABLE E-9 Breakout of Clinical Sciences Workforce, 2006-2016, Scenario 2.   CLINICAL - SCENARIO 2 DETAILS   US Male US Female Foreign Male Foreign Female 2006 9,457 14,706 6,359 4,798 2007 9,887 15,716 6,388 4,868 2008 10,408 16,886 6,417 4,944 2009 11,040 18,252 6,446 5,026 2010 11,808 19,859 6,475 5,115 2011 12,741 21,765 6,505 5,211 2012 13,877 24,040 6,534 5,315 2013 15,259 26,773 6,564 5,427 2014 16,943 30,076 6,594 5,549 2015 18,995 34,088 6,624 5,682 2016 21,496 38,982 6,654 5,825 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences DEMOGRAPHIC DETAILS FOR SCENARIO 3 (LOW RISK) Figure E-11 shows the projections for each of the four demographic groups for the biomedical sciences workforce for Scenario 3 in bar-graph form, and Table E-10 shows the same projections in table form. FIGURE E-11 Breakout of biomedical sciences workforce, 2006-2016, scenario 3. SOURCE: NRC analysis. TABLE E-10 Breakout of Biomedical Sciences Workforce, 2006-2016, Scenario 3   BIOMEDICAL - SCENARIO 3 DETAILS   US Male US Female Foreign Male Foreign Female 2006 80,268 45,828 23,636 10,121 2007 80,747 46,823 24,295 11,060 2008 81,255 47,858 25,008 12,175 2009 81,792 48,934 25,776 13,494 2010 82,358 50,051 26,602 15,052 2011 82,953 51,211 27,490 16,889 2012 83,577 52,416 28,444 19,052 2013 84,230 53,666 29,465 21,597 2014 84,913 54,963 30,559 24,588 2015 85,626 56,308 31,730 28,101 2016 86,369 57,702 32,981 32,223 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Figure E-12 shows the projections for each of the four demographic groups for the behavioral sciences workforce for Scenario 3 in bar-graph form, and Table E-11 shows the same projections in table form. FIGURE E-12 Breakout of behavioral sciences workforce, 2006-2016, scenario 3. SOURCE: NRC analysis. TABLE E-11 Breakout of Behavioral Sciences Workforce, 2006-2016, Scenario 3   BEHAVIORAL - SCENARIO 3 DETAILS   US Male US Female Foreign Male Foreign Female 2006 57,593 62,758 1,457 2,484 2007 57,491 63,830 1,605 2,735 2008 57,391 64,907 1,750 3,003 2009 57,293 65,990 1,892 3,291 2010 57,197 67,078 2,031 3,600 2011 57,102 68,172 2,167 3,932 2012 57,010 69,273 2,301 4,287 2013 56,920 70,379 2,432 4,669 2014 56,831 71,493 2,560 5,078 2015 56,744 72,613 2,686 5,518 2016 56,659 73,739 2,809 5,991 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Figure E-13 shows the projections for each of the four demographic groups for the clinical sciences workforce for Scenario 3 in bar-graph form, and Table E-12 shows the same projections in table form. FIGURE E-13 Breakout of clinical sciences workforce, 2006-2016, scenario 3. SOURCE: NRC analysis. TABLE E-12 Breakout of Clinical Sciences Workforce, 2006-2016, Scenario 3   CLINICAL - SCENARIO 3 DETAILS   US Male US Female Foreign Male Foreign Female 2006 9,457 14,706 6,359 4,798 2007 9,591 15,283 6,439 4,978 2008 9,728 15,890 6,520 5,181 2009 9,869 16,528 6,604 5,408 2010 10,013 17,199 6,689 5,661 2011 10,160 17,904 6,777 5,944 2012 10,311 18,645 6,866 6,259 2013 10,466 19,424 6,958 6,608 2014 10,624 20,242 7,052 6,995 2015 10,785 21,101 7,148 7,424 2016 10,950 22,004 7,246 7,897 SOURCE: NRC analysis.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences DESCRIPTION OF DATA USED FOR WORKFORCE PROJECTIONS Table E-13 shows the data for U.S.-trained Ph.D.s. In Table E-13, the values in the rightmost columns are the average annual growth rates using the past 5 years of data (i.e., 2001 to 2006) and the past 7 years of data (i.e., 1999 to 2006). The numbers in these columns that are shaded gray are the annual growth rates used for those demographic groups in the workforce projections. To mitigate large changes, the smaller of the two annual growth rates is typically used, or the most reasonable value is used based on inspection. TABLE E-13 Data for U.S.-Trained Ph.D.s SOURCE: Data adapted from National Science Foundation Survey of Doctoral Recipients, 1995-2006.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences Table E-14 shows the data for foreign-trained Ph.D.s. It should be noted that information regarding foreign-trained Ph.D. students is not as well documented as the information for U.S.-trained Ph.D. students. In Table E-14, the values in the rightmost column are the average annual growth rates using the past 3 years of data (e.g., 2003 to 2006) because there are no data available for 2001. These are the annual growth rates used for the various foreign-trained Ph.D. groups in the workforce projections. Where there are “blanks” in the 2003 or 2006 data, values have been assumed to be the same as either the preceding data or the succeeding data. These cells are shaded gray and will show no growth between 2003 and 2006 because the same numbers are used for both years. TABLE E-14 Data for Foreign-Trained Ph.D.s SOURCE: Dara adopted from National Science Foundation Survey of College Graduates, 1995-2006.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences DESCRIPTION OF SYSTEM DYNAMICS MODELS System dynamics (SD) is the application of feedback control systems principles and techniques to managerial, organizational, and socioeconomic problems. As such, the methodology seeks to bring together multiple views or aspects of the same problem under study and integrate them into a conceptual and meaningful whole. In fact, most difficulties to fully understanding complex issues arise from looking independently at various elements of an issue instead of considering pertinent interrelations. Consequently, optimization is sought for each separate element in the system, which inadvertently leads to sub-optimization of total system performance. With SD, it is possible to take hypotheses about the separate parts of a system, to combine them in a computer simulation model, and to learn both the “local” and “global” consequences of decisions and actions, as well as the impact of these decisions and actions on short-term and long-term performance. Most of the time, the impact on short-term and long-term performance are opposite: an action that looks positive in the short-term is often very detrimental in the long-term. Conversely, an action that produces favorable long-term performance must usually suffer poor performance in the short-term. SD extends modeling methods traditionally associated with engineering design and feedback control theory into the arena of policy evaluation and management decision making. The following characteristics distinguish SD models from traditional decision support methodologies: Its building blocks are feedback loops; It can accommodate non-linear relationships among variables; It enforces causality; It can include delays; It can model “soft” variables; It can model management policies; and It presents a dynamic environment for decision analysis. These characteristics are important because they allow SD models to capture the key structural relationships that define a social system. The structure, in turn, produces the dynamic behavior of interest. The resulting simulation mirrors reality because the underlying model structure includes the appropriate feedback loops, causality, delays, and other relationships. SD models include real-world causal logic, which allows someone to trace through the model to see why things happen the way they do. The SD modeling and simulation approach is different from traditional statistical approaches in several ways. First, the models are more realistic because they capture cause-and-effect linkages, feedback loops, delays, non-linear relationships, and management policies. Second, the simulations are more accurate and reliable because they provide a sanity check on assumptions and are more rigorous than mental models or spreadsheets, allow for analysis of a wider range of issues, and identify the actions that are most effective (and least effective) for improving performance. Third, communication is more effective because the approach is graphical (the connections are easily seen and understood), logical (the results can be traced back to their root causes), and experiential (we learn best by doing and simulation is a good substitute for the real world). In SD models, a “stock” and “flow” methodology is used in which stocks represent accumulations of “things” (e.g., people, inventory), and flows are the movement of these “things” into, out of, and between stocks (Figure E-14). For Scenario 1 (moderate risk) and Scenario 2 (high risk), a very basic SD model was used in which the stocks represent groups of people in the following categories (which were established based on available data): In Science and Engineering (S&E)—The number of people employed in science and engineering positions (not considered postdoctorates). Out of S&E—The number of people employed in areas other than science and engineering. Unemp Seeking Work—The number of people currently unemployed but are seeking work. Unemp Not Seeking Work—The number of people currently unemployed but not seeking work, but are not retired. Retired—The number of people currently retired. Postdoctorate—The number of people employed as postdoctorates. The total number of people considered in the “workforce” is the sum of all people that are not retired. Thus, the workforce for any particular demographic group (e.g., U.S.-trained males in biomedical science) is the following: Workforce = In S&E + Out of S&E + Unemp Seeking Work + Unemp Not Seeking Work + Postdoctorate The flows in and out of the stocks (e.g., In 1, Out 1) are based on growth rates determined from the data for the specific demographic group and shown earlier in Tables E-13 and E-14. If the growth rate is greater than zero (i.e., positive), then people are added to the stock through the In flow. If the growth rate is less than zero (i.e., negative), then people are removed from the stock through the Out flow. The amount of people that are added or removed is based on the percentage growth rate multiplied by the current number of people in the stock. For example, if 100 people were in a stock and the growth rate is 5 percent, then 5 people would be added to the stock during that simulation step. Figure E-14 below shows this stock-and-flow diagram for the U.S.-trained males in biomedical science. This exact same model structure is used for all other demographic

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-14 Model for U.S.-trained males in biomedical science for scenarios 1 and 2. groups (e.g., U.S.-trained females in biomedical science, foreign-trained males in clinical science, etc.). However, different data are used to initialize the model based on which specific demographic group is being modeled. For Scenario 3, a slightly different stock-and-flow structure is used that includes more of the “supply pipeline” (Figure E-15). For each demographic group, a stock of Ph.D. students is also included that precedes the stock for the entire workforce. (At this point, because the data for Ph.D. students is aggregate, the workforce is represented as aggregate to maintain consistency, as opposed to multiple portions of the workforce as in Scenarios 1 and 2 and in Figure E-14.) The inclusion of the supply pipeline in Scenario 3 is the reason that this scenario is considered low risk. Adding the Ph.D. student pool produces limits to the growth of the following workforce, which is more realistic than letting the workforce

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences FIGURE E-15 Model for U.S.-trained females in biomedical science for scenario 3. continue to grow (or shrink) at its current pace. Consequently, the workforce projection numbers are lower for all three major workforces (i.e., biomedical science, clinical science, and behavioral science). In the pipeline model for each demographic group, the model starts with the number of Ph.D. students and uses the growth rate for Ph.D. students to determine how many Ph.D. students enter the Ph.D. pool. The Avg Grad Length then determines how quickly students move through the Ph.D. pool to enter the workforce. For the purposes of this analysis, the average graduation time is assumed to be 7 years. Thus, 1/7th of the Ph.D. pool enters the workforce each year. For the Workforce, the Avg Work Length determines how many people retire or move out of the workforce each year. For the purposes of this analysis, the average time that someone spends in the workforce is assumed to be 50 years. Thus, 1/50th of the people leave the workforce each year of the simulation. Table E-15 shows the data used for the Ph.D. pipeline model. The values in the rightmost columns are the average annual growth rates using the past 5 years of data (i.e., 2001 to 2006), as highlighted by the gray shaded cells. The 5-year average annual growth rates are the ones used in the Scenario 3 model for the growth of the Ph.D. student population. It should be noted that the pipeline model is not complete. Additional stocks could precede the Ph.D. pool (e.g., undergraduate students, K-12 students, etc.) to represent the full pipeline of students progressing up to employment in the workforce. In addition, based on detailed data for the Ph.D. pool, several pipeline models could be used to show the movement through the pipelines for the fields of science, engineering, etc. in addition to the separation of male/female and U.S./foreign.

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Research Training in the Biomedical, Behavioral, and Clinical Research Sciences TABLE E-15 Ph.D. Data Used in Scenario 3

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