NSF relies on two programs for bringing rotators into the agency: (1) the IPA program and (2) the VSEE program. The Office of Personnel Management develops policies on agencies’ use of the IPA program and promulgates program regulations. Rotators in NSF’s IPA and VSEE programs differ in key respects, including their employment status and compensation. IPA rotators. NSF enters into written agreements with rotators’ home institutions for all IPA assignments. The agreements detail rotators’ salaries and health, retirement, and other fringe benefits at their home institutions, as well as the cost-sharing amounts NSF and home institutions are to pay during rotators’ assignments. NSF reimburses its cost-sharing amounts to home institutions, which continue to pay rotators’ full salaries and benefits. NSF does not cap the salaries of IPA rotators; as a result, IPA rotators may receive salaries that exceed the maximum federal salary for the position they hold at NSF. In contrast, if an IPA rotator’s salary is less than the minimum federal salary for the position, NSF will supplement the salary to the minimum rate. VSEE rotators. NSF appoints VSEE rotators as federal employees on a nonpaid leave of absence from their home institutions. VSEE rotators receive their salaries directly from NSF but are not eligible for certain federal benefits, such as retirement; instead, NSF reimburses home institutions for the employer’s share of retirement, life insurance, and health benefits that would otherwise be discontinued. NSF’s policy is to set salaries for VSEE rotators that are generally comparable to the salaries the rotators would receive at their home institutions. In setting salaries, NSF also takes into account other sources of income, such as consulting, and allows for locality pay adjustments applicable to employees in the Washington, D.C., metropolitan area. However, because VSEE rotators are federal employees, NSF caps their salaries at the federal maximum for the position they hold at NSF. Both IPA and VSEE rotators are eligible for certain other types of reimbursement. In particular, rotators have the option of having NSF pay their moving expenses to and from Washington, D.C., or receiving per diem allowances in accordance with federal travel regulations for up to 2 years. In addition, NSF may reimburse rotators for travel-related expenses related to their participation in NSF’s Independent Research and Development program, which enables NSF staff to maintain their involvement with their professional research and research-related activities at their home institutions. Table 1 shows additional information on IPA and VSEE rotator expenses. Rotators are generally assigned to one of NSF’s seven directorates that support science and engineering research and education (see table 2). Each directorate is headed by an assistant director and deputy assistant director. Directorates are further subdivided into divisions, offices, or sections. Each division is headed by a division director and typically a deputy division director, and each office is headed by an office director and typically a deputy office director. All these positions are executive positions at NSF. At the staff level, NSF uses program directors—subject matter experts in the scientific areas they manage—to conduct reviews of proposals and recommend which projects the agency should fund. With an annual budget of about $7.5 billion, NSF funds approximately 24 percent of all federally supported basic research conducted by colleges and universities in the United States. In 2016, NSF established the Steering Committee for Policy and Oversight of the IPA Program. The steering committee serves as the primary body for considering policy on NSF’s use of IPA rotators and overseeing common approaches to budgeting and implementation of the IPA program. The committee’s membership includes NSF’s chief human capital officer, who serves as the chair, and several other NSF officials. The steering committee has established strategic principles for management of the IPA program. These principles include maintaining a balance between IPA rotators and federal staff and a commitment to ongoing improvement of the program. NSF officials told us that there is no similar steering committee for overseeing VSEE rotators. Instead, each VSEE rotator is individually overseen by his or her respective supervisor. For the agency as a whole, NSF’s Office of Information and Resource Management and its Division of Human Resource Management conduct human capital management. NSF officials stated that the head of the Office of Information and Resource Management serves as the Chief Human Capital Officer and develops and oversees NSF’s human capital approaches and strategies. These officials also told us that the Deputy Chief Human Capital Officer serves as the division director of Human Resource Management and is responsible for administering the division’s day-to-day operations. The Division of Human Resource Management administers the agency’s human capital policies as set forth in NSF’s personnel manual. The numbers of rotators and their costs to NSF in proportion to other staff have remained relatively stable. Most rotators were IPA rotators, and were used in both executive and program director (staff-level) positions. NSF generally used VSEE rotators in program director positions. Most rotators at NSF were IPA rotators, and the proportion of rotators relative to other staff has remained relatively stable over time (see fig. 1). During the 10-year period we reviewed, from fiscal year 2008 through fiscal year 2017, IPA and VSEE rotators comprised about 12 percent and about 3 percent, respectively, of NSF’s total workforce; and the number of IPA rotators ranged from 162 to 190 (about 11 to 12 percent of total staff), and the number of VSEE rotators ranged from 22 to 52 (about 1 to 3 percent of total staff). NSF primarily used rotators across its seven scientific directorates, using IPA rotators in executive and program director positions and VSEE rotators in program director positions. The agency used rotators in these positions alongside NSF’s permanent staff to perform day-to-day agency operations, including managing the agency’s merit review process for determining which projects to fund. NSF used IPA rotators in executive positions such as assistant director. According to agency officials, individuals in executive positions at NSF are responsible for setting the direction for the scientific area they are assigned, leading scientific and technical matters, establishing an organizational culture, overseeing outreach and collaboration with NSF stakeholders, and contributing to NSF and national policy development and implementation. For example, an executive IPA rotator that we interviewed told us that he emphasized forming partnerships with industry when setting the direction for his directorate, including issuing joint solicitations for research proposals with industry partners. In addition, according to NSF officials, individuals in executive positions provide guidance and team management for staff. The proportion of IPA rotators to federal employees in executive positions within NSF’s seven scientific directorates and other staff offices has generally increased since fiscal year 2012. As shown in figure 4, from fiscal year 2008 through fiscal year 2017, the number and proportion of executive positions filled by IPA rotators ranged from 18 of 98 (about 18 percent) in 2008 to 30 of 108 (about 28 percent) in fiscal year 2016. In November 2017, IPA rotators filled 29 of 88 (about 33 percent) executive positions within NSF’s seven scientific directorates. At that time, the proportion of executive positions filled by IPA rotators varied among directorates, as shown in table 3. For example, IPA rotators filled 4 of 8 (50 percent) of the executive positions in the Directorate for Social, Behavioral, and Economic Sciences and 2 of 14 (about 14 percent) of the executive positions in the Directorate for Mathematical and Physical Sciences. According to NSF officials, NSF often pairs IPA rotators and federal employees at the executive level so that each can benefit from the other’s experience and perspective. For example, in all but one directorate, an IPA rotator filled the assistant director position and a federal employee filled the corresponding deputy assistant director position. Two NSF executives we interviewed, including an IPA rotator and a federal employee, commented positively on the pairing of IPA rotators and federal employees at the executive level. For example, they said that rotators maintain close ties to the research community and federal employees may have more experience with NSF’s institutional history. One NSF executive told us that IPA rotators help keep the agency at the forefront of science because they have deep ties with the research community and regularly publish their own research. Additionally, a federal program director we interviewed told us that in one previous instance in which an IPA rotator filled an executive position without being paired with a federal employee, the rotator’s lack of institutional knowledge of NSF and the steep learning curve for the position caused inefficiencies during the rotator’s first year at NSF. The agency, however, does not require pairing IPA rotators and federal employees at the executive level, according to NSF officials. For example, in November 2017, IPA rotators filled both the division director and deputy division director positions in the Division of Behavioral and Cognitive Science and Division of Undergraduate Education. In our interviews with a nongeneralizable sample of NSF employees and rotators, we found mixed perceptions about the effect of NSF’s use of IPA rotators on opportunities for advancement for permanent employees. For example, in response to a question about this effect, one permanent NSF employee told us that she advanced to an executive position and that opportunities exist for advancement within the agency. In contrast, another NSF employee we interviewed told us that she did not feel there were opportunities for advancement because, in her view, executive vacancies created by the departure of rotators were exclusively filled with other rotators. NSF officials said that the agency has no policy that restricts repeatedly filling certain executive positions with rotators and that such a situation is a common practice. Nevertheless, NSF officials told us 32 of the 88 executives (about 36 percent) in NSF’s seven scientific directorates in November 2017 had held staff-level positions within the agency before becoming executives. NSF uses both IPA and VSEE rotators in program director positions, which are staff-level positions. In fiscal year 2016, NSF had a total of 506 program directors, including 139 IPA rotators (about 27 percent) and 39 VSEE rotators (about 8 percent). According to NSF officials, program directors are responsible for conducting long-range planning and developing budgets for the areas of science represented by their program and for administrating the merit review process. In particular, IPA and VSEE rotators who serve as program directors help determine the projects that NSF funds. To do so, they review proposals, identify experts in their field to serve as external reviewers, and make funding recommendations to their respective division directors. NSF officials told us that, similar to the pairing of IPA rotators and federal employees at the executive level, permanent and rotating program directors frequently work together on a shared program so that each can benefit from the other’s experience and perspective. For example, a rotating program director we interviewed told us that she worked under the guidance of a program lead, who is typically a permanent employee. Another rotating program director told us that NSF’s permanent federal employees are good at training incoming rotators. Beginning in fiscal year 2017, NSF adopted rotator program cost- management strategies expected to achieve the greatest savings with the least harm to recruitment, but NSF officials said it is too soon to determine the full results because these new strategies are being phased in for new IPA agreements only. NSF considered other strategies to manage rotator costs, but it did not adopt them, generally because NSF anticipated negative effects on rotator recruitment or because it estimated the resulting cost savings would be small. NSF has adopted three strategies to manage rotators’ costs in fiscal year 2017, but, NSF officials said it is too soon to determine the full results because these new strategies are being phased in for new IPA agreements only. All three of these strategies relate to IPA rotators; NSF officials told us that they have not considered or adopted any cost- management strategies related to VSEE rotators. The officials explained that any such strategies could affect NSF’s entire federal workforce because VSEE rotators are federal employees. The three strategies are: (1) obtaining a minimum 10 percent cost-share from each IPA rotator’s home institution, (2) limiting IPA rotators’ paid trips to their home institutions to 12 per year, and (3) no longer reimbursing IPA rotators for consulting income that they forgo while at NSF. NSF officials told us they expect to issue a report with the results of evaluations of all three strategies in December 2018. In October 2016, NSF implemented a cost-sharing pilot program that requires institutions covered by the program—those who entered into negotiations for new IPA agreements in fiscal year 2017—to pay for at least 10 percent of the IPA rotators’ salaries and fringe benefits. Implementing this cost-management strategy, and the other strategies that NSF adopted, was consistent with recommendations from NSF’s steering committee for oversight of IPA rotators. This cost-management strategy targeted NSF’s costs for IPA rotators’ salary and fringe benefits, which constitute the largest component of IPA rotators’ costs. For example, these costs were about $34.7 million, or about 89 percent of IPA rotator costs in fiscal year 2017. Previously, according to NSF officials, the agency requested an optional cost-share amount of 15 percent from rotators’ home institutions, but it typically received less because of variations in the amounts that home institutions provided. According to an October 2016 report from the task force on fiscal oversight, NSF decided on 10 percent for the cost-sharing pilot program because, historically, few home institutions provided the full 15 percent and NSF believed a requirement of 10 percent would not significantly affect its ability to recruit and hire IPA rotators. If a home institution is unable to provide the full 10 percent, the institution may request that NSF waive the cost-sharing requirement. According to NSF officials, such requests must be signed by a senior administrator at the rotator’s home institution and include the rationale for not being able to provide the required amount, the financial impact on the institution if it were to provide the full 10 percent, and associated documentation, among other things. Changes made in implementing this strategy, and the other strategies that NSF adopted, applied to new IPA agreements made in fiscal year 2017. These changes did not apply to IPA rotators with agreements made prior to 2017—even if those agreements are subsequently extended or renewed—or that were being negotiated at the time of the policy change, provided that the rotators’ appointment memoranda were already being reviewed by NSF’s Division of Human Resource Management. NSF officials told us that as of March 2018, the agency had not conducted full evaluations of this strategy or the other strategies because it was too soon to determine their full effects and NSF had not yet collected enough data to do so. Instead, NSF issued reports in January and March 2018 containing its preliminary analyses. In general, these preliminary reports found that the cost-management strategies resulted in savings to NSF. Similarly, our analysis of data from NSF found that cost sharing as a percentage of IPA rotators’ salary and fringe benefits increased from about 7 percent in fiscal year 2016 to about 8 percent in fiscal year 2017. NSF officials told us that of the 55 IPA rotators who were subject to the cost-sharing requirement in fiscal year 2017: the home institutions for 54 rotators met or exceeded the 10 percent cost-share requirement, and of those, 16 exceeded the cost-share requirement; and the home institution for 1 rotator did not cost-share because the rotator was from a Federally Funded Research and Development Center and NSF waived the cost-share requirement because cost- sharing would not decrease the overall federal cost. In November 2017, NSF decided to extend the cost-sharing pilot through at least the end of fiscal year 2018, to ensure a full evaluation could be conducted. In particular, NSF officials told us that they need more data and experience with this pilot program to better understand its effects, such as the ability to recruit potential IPA rotators. For example, one IPA rotator that we interviewed expressed concern with the cost-sharing requirement’s potential effect on small or publicly funded universities, which may lack funds to contribute to the cost of an IPA assignment. According to NSF officials, their evaluation will include an analysis of the cost of IPA rotators under the cost-sharing requirement and its effect on the IPA program, including recruitment. Beginning in fiscal year 2017, for IPA rotators who entered into negotiations for new agreements in that fiscal year, NSF placed a limit of 12 agency-funded trips per year that rotators may take to their home institutions under the Independent Research and Development program. In our analysis of data from NSF, we found that NSF’s costs for IPA rotators under this program decreased from about $1.5 million (about 3 percent of IPA rotator costs) in fiscal year 2016 to $1.1 million (about 3 percent of IPA rotator costs) in fiscal year 2017. NSF officials told us that the new limit applies only to an IPA rotator’s trips to their home institution and does not limit travel to other locations for fieldwork or scientific conferences, among other things. These officials explained that NSF chose not to limit trips to these other locations because they are considered fundamental to IPA rotators’ research and are infrequent—occurring one to three times per year, on average, per IPA rotator. Additionally, rotators are permitted to use annual leave, leave without pay, or flexitime to take trips using non-NSF funds for activities performed on a rotator’s own time. In adopting this cost-management strategy, NSF sought to balance the benefits of IPA rotators’ travel with the travel costs. According to the Task Force on Fiscal Oversight’s October 2016 report, NSF’s support for travel benefits the agency by providing a way for program directors and executives to stay current in their scientific fields, conduct outreach with scientific communities, and provide oversight and stewardship of NSF’s programs and awards. NSF officials told us that the agency sought to control travel costs under the Independent Research and Development program by setting a reasonable limit to NSF-funded trips that would cause the least harm to rotators’ research so as not to discourage them from coming to NSF. As a result, NSF decided on a maximum of 12 trips per year under this program because, historically, more than 80 percent of the IPA rotator participants traveled to their home institution less than once per month. In fiscal year 2017, for IPA rotators who entered into new agreements in that fiscal year, NSF ended reimbursements for consulting income that the rotators forgo as a result of their assignment to NSF. Previously, when an IPA rotator discontinued consulting activities during an IPA assignment, NSF would reimburse the rotator up to $10,000 a year. IPA rotators who entered into negotiations or agreements with NSF prior to this change may still receive this reimbursement. In fiscal year 2017, NSF’s cost for lost consulting reimbursements to IPA rotators was $150,000. This amount represented a decrease of about $160,000, or about 52 percent, from fiscal year 2016. NSF made this change because it determined that doing so would not negatively affect the IPA program. In particular, NSF found that other federal science agencies typically did not reimburse IPA rotators for lost consulting income and it concluded that IPA rotators typically do not expect NSF to offer reimbursement. In addition to the three adopted strategies, NSF’s Task Force on Fiscal Oversight identified other potential cost management strategies for the IPA program. The task force reviewed various data on the costs that make up the IPA program, such as the number of IPA rotators who received a particular form of compensation or who would be affected by the potential strategies. In addition, the task force took into account anecdotal and other evidence on how IPA rotators might react to the strategies. Using input from the task force, NSF opted against the other potential strategies because it either (1) expected the resulting cost savings to be small or (2) anticipated potential negative effects from implementing them, such as increased difficulty in hiring IPA rotators. These potential cost-management strategies primarily related to IPA rotator compensation, as described below. Capping IPA rotators’ salaries. NSF decided against establishing a salary cap for IPA rotators at various levels between about $185,000 and $240,000 annually. The task force found that salary caps at lower levels would have greater cost savings because of the higher number of individuals covered by the cap, but that the caps would also pose a significant risk to NSF’s ability to recruit IPA rotators. In particular, the task force found that salary caps at lower levels would disproportionately affect IPA rotators in two of its directorates—the Directorate for Computer and Information Science and Engineering and the Directorate for Engineering—because of the higher salaries of individuals in positions associated with those fields. As a result, the task force recommended that NSF first assess the effects of its cost-sharing pilot program before proceeding with any cap on IPA rotators’ salaries. Reducing or eliminating IPA rotators’ supplemental pay. NSF decided against reducing or eliminating the supplemental pay that IPA rotators receive when their salary at their home institution is below the minimum for their NSF position. In fiscal year 2017, NSF’s cost for IPA rotators’ supplemental pay was $1.0 million (about 3 percent of IPA rotator costs). The task force recommended against this potential cost-management strategy because it would disproportionately affect IPA rotators in two of its directorates—the Directorate for Biological Sciences and the Directorate for Geosciences. In addition, the task force expected that any cost savings associated with this strategy would be small. Reducing IPA rotators’ per diem payments. NSF decided against reducing or eliminating per diem payments for lodging (excluding taxes), meals, and incidental expenses incurred during the length of rotators’ assignments. In fiscal year 2017, NSF’s cost for per diem payments was $3.1 million (about 8 percent of IPA costs). The task force concluded, based on its analysis of per diem costs and anecdotal evidence, that many IPA rotators would opt to depart NSF if NSF did not provide per diem payments. As a result, the task force recommended against this strategy. As of June 2018, NSF had not developed an agency-wide workforce strategy for using rotators, as its IPA program steering committee recommended. In addition, NSF has not fully evaluated or developed plans to evaluate both IPA and VSEE rotator program results in terms of progress toward NSF’s human capital goals or programmatic results. As of June 2018, NSF had not developed an agency-wide workforce strategy that includes use of rotators, as NSF’s IPA program steering committee had recommended. In an August 2016 report on the IPA program, the steering committee stated that NSF did not have an agency- wide workforce strategy; instead, each directorate made decisions on its own about when and how to use IPA rotators in executive and program director positions. According to the report, an agency-wide framework would enable NSF to ensure an optimal balance of federal and rotator executives and program directors, which is a strategic principle that the steering committee developed for the IPA program. In February 2017, the committee issued an internal report to agency leadership that recommended expanding what was originally envisioned as a workforce strategy for the IPA program into a comprehensive agency-wide workforce strategy. The report stated that expanding the scope of the workforce strategy would have the greatest impact across the agency and would help NSF leadership in making strategic human capital decisions. The report outlined a process for developing a workforce strategy with various steps, including the following: Job analyses. The report recommended job analyses to review the roles and responsibilities of executive and staff-level positions and to identify the skills and capabilities required for successful performance of the work. According to the report, the steering committee’s working group for developing a workforce strategy found, based on its initial efforts to review position descriptions and roles and responsibilities, that some functions may be better served if performed by permanent federal employees and other functions by rotators. However, the working group concluded that NSF should obtain additional input and evidence before initiating large-scale changes in its workforce. Analysis of workforce gaps and surpluses. The report stated that identifying gaps and surpluses in the demand and supply for federal and rotator scientific staff would inform opportunities to optimize recruitment and retention efforts. The report recommended separate analyses for executive and scientific staff- level positions. Development of strategies to close workforce gaps and address surpluses. According to the steering committee’s report, examples of strategies include succession planning and rebalancing the mix of permanent federal staff and rotators to ensure an optimal workforce with the skills, experience, and capabilities to accomplish NSF’s science-related work. According to NSF officials, the agency’s Division of Human Resource Management was responsible for implementing the steering committee’s recommendation. In particular, it undertook an effort to work with senior leadership to develop a broad strategic workforce plan for the agency. However, in June 2018, NSF officials told us that they shifted their focus from developing a separate workforce strategy in order to focus instead on (1) development of a human capital operating plan, which agencies are required to develop and approve annually, and update as needed, under OPM regulations that went into effect on April 11, 2017; and (2) an Office of Management and Budget (OMB) memorandum issued in April 2017 directing agency heads to develop reform plans that identify ways to improve the efficiency, effectiveness, and accountability of their respective agencies. The NSF officials explained that they recognized the value in having a workforce strategy, but they did not consider it appropriate for the Division of Human Resource Management to develop a workforce strategy at the same time that the agency was completing the OPM and OMB plans. NSF did not specify how its efforts to complete the OPM and OMB plans would address the need the steering committee identified for an agency- wide framework that would enable NSF to ensure an optimal balance of federal and rotator executives and program directors. In particular, NSF’s human capital operating plan, which it approved in April 2018, does not discuss NSF’s use of rotators or include information on balancing the agency’s use of rotators with permanent staff. Furthermore, NSF has not yet determined how it will address its use of rotators as part of its agency reform plan. In particular, NSF officials told us in June 2018 that they may address the agency’s use of rotators under the workforce focus area of its reform plan, but that they were only just beginning to identify and select initiatives under this focus area and that these initiatives have not yet been finalized. The process the NSF steering committee laid out in its internal report, when implemented, would align with two key principles GAO has identified for effective strategic workforce planning. Specifically, it would align with the principles of (1) determining the skills and competencies that are critical to successfully achieving missions and goals, and (2) developing human capital strategies to address gaps and enable the contribution of critical skills and competencies needed for mission success. By incorporating the NSF’s steering committee’s recommendation for a workforce strategy—and the process outlined by the steering committee for developing this strategy—into its human capital operating plan or agency reform plan, NSF could better manage its use of rotators and balance them with its permanent staff. We have previously found that high-performing organizations recognize the fundamental importance of measuring both the outcomes of human capital strategies and how these outcomes have helped the organizations accomplish their missions and programmatic goals. However, as of May 2018, NSF had not fully evaluated and did not have plans to evaluate the results of its IPA and VSEE rotator programs in terms of progress toward human capital goals and the contributions the programs made toward achieving programmatic results. One of GAO’s key principles for effective strategic workforce planning states that agencies should monitor and evaluate progress toward the agencies’ human capital goals and the contribution that human capital results have made toward achieving programmatic results. In particular, we previously found that evaluation activities can improve the effectiveness of workforce strategies by identifying shortfalls in performance and other improvement opportunities. OPM also requires agencies to develop a human capital operating plan that will support the evaluation of the agency’s human capital strategies. In March 2014, NSF published a summary of the results of focus groups with IPA rotators and their supervisors. This summary outlined benefits and challenges of the program from the perspectives of both groups, such as the benefit of bringing fresh perspective and new ideas to NSF and the challenge of recruiting and retaining qualified IPA rotators. However, the summary did not provide the agency’s assessment of progress towards programmatic results and human capital goals. For example, it summarized the benefits of the program from the standpoint of rotators and did not provide NSF’s assessment of how individual IPA rotators or the program as a whole contributed to NSF’s scientific mission. In addition, the summary did not provide an assessment of the extent to which the current workforce balance of federal and rotator executives and program directors is aligned with NSF’s work. In our semistructured interviews with federal staff and rotators in executive and staff-level positions at NSF, most were comfortable with the current balance, but three individuals raised concerns about the use of rotators in executive positions, suggesting that NSF could benefit from further analysis of its balance of rotators and federal staff. In April 2018, NSF adopted its human capital operating plan which identifies specific, short-term actions that the agency will take to achieve its human capital goals. In its plan, NSF identified strategies derived from NSF’s commitment to ongoing improvement, such as reviewing and realigning its workforce to meet future needs. Also, NSF’s process for developing a workforce strategy, outlined in the steering committee’s February 2017 internal report, included recommendations to conduct an assessment of the outcomes of workforce strategies and the impact of these outcomes on helping NSF accomplish its scientific mission and related programmatic goals. However, plans for this assessment did not include an evaluation of the agency’s rotator programs. Moreover, neither the steering committee’s February 2017 internal report nor NSF’s April 2018 report committed to conducting such an evaluation or specified how assessments described in its reports would address NSF’s rotator programs. For example, neither report specified how NSF would evaluate the extent to which the rotator programs have achieved NSF’s objectives, which we identified through our review of NSF documentation and interviews with NSF officials. These objectives include: bringing fresh perspectives from across the country and across all fields of science and engineering supported by NSF; helping influence new directions for research in science, engineering, and education, including emerging interdisciplinary fields; providing scientific leadership and management of NSF’s research and education programs; and providing opportunities for researchers to gain first-hand knowledge of the philosophy and mechanisms of federal support for research and bring this knowledge back to their home institutions. According to NSF officials, the agency has not separately evaluated the results of its rotator programs in part because rotators are blended into its permanent federal workforce, making it difficult to evaluate the results of its rotator programs separately from those of its overall workforce. In our December 2003 report on key principles for effective strategic workforce planning, we found that federal agencies in general have experienced difficulties in defining practical and meaningful measures that assess the effects human capital strategies have on programmatic results. However, without an evaluation of the extent of the rotator programs’ contributions toward NSF’s human capital goals or programmatic results, NSF is limited in its ability to demonstrate the programs’ benefits to external stakeholders, such as the Congress, and to adjust the programs, if warranted. Such adjustments could include increasing or decreasing the use of rotators overall or in certain types of positions, such as executive or staff-level positions. In recent years, NSF has recognized the need to think more strategically about its use of rotators and has taken positive steps to manage its rotator programs. For example, beginning in fiscal year 2017, NSF adopted several strategies to manage the cost of rotators. However, as of June 2018, NSF had decided against developing a separate agency-wide strategy for balancing its use of IPA rotators and federal staff, as NSF’s steering committee for the IPA program recommended in February 2017. NSF officials said that they recognized the value in having a workforce strategy but wanted to focus instead on addressing OPM and OMB requirements related to workforce planning. By following through on the steering committee’s recommendation for a workforce strategy, NSF could better manage its use of rotators and balance them with its permanent staff. Moreover, as of June 2018, NSF had not fully evaluated the results of the rotator programs, as called for by key principles for effective strategic workforce planning. NSF officials told us they have not done so, in part, because rotators are blended into NSF’s permanent federal workforce, making it difficult to evaluate the results of its rotator program separately from those of its overall workforce. However, without an evaluation of the extent of the rotator programs’ contributions toward NSF’s human capital goals or programmatic results, NSF is limited in its ability to demonstrate the programs’ benefits to external stakeholders, such as the Congress, and to adjust the programs, if warranted. We are making the following two recommendations to NSF: The NSF Director of Human Resource Management should complete the development of an agency-wide workforce strategy for balancing the agency’s use of IPA and VSEE rotators with permanent staff as part of NSF’s current agency reform planning efforts or updates to its human capital operating plan. (Recommendation 1) The NSF Director of Human Resource Management should evaluate the contributions of the IPA and VSEE rotator programs toward NSF’s human capital goals and the contributions the programs have made toward achieving programmatic results. (Recommendation 2) We provided a draft of this report to NSF for comment. In its written comments, which are reproduced in appendix I, NSF concurred with our recommendations and stated that implementation of the recommendations will enhance efforts to fulfill the agency’s mission and strengthen its workforce. NSF also provided technical comments, which we incorporated as appropriate. We are sending copies to the appropriate Congressional Committees, the Director of the National Science Foundation, and other interested parties. In addition, the report is available at no charge on the GAO website at http://www.gao.gov. If you or your staff have any questions about this report, please contact me at (202) 512-3841 or neumannj@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. GAO staff who made key contributions to this report are listed in appendix II. In addition to the individual named above, Joseph Cook (Assistant Director), Nkenge Gibson, Kathryn Smith, and Douglas Hunker made key contributions to this report. Also contributing to this report were Antoinette Capaccio, Serena Lo, Timothy Guinane, Cynthia Norris, and Sara Sullivan.

Answer: NSF has identified potential benefits and challenges associated with its use of rotators. Benefits include fresh perspectives and close connections to the scientific community, while challenges include staffing turnover and higher costs for some rotators compared with permanent employees. GAO was asked to review NSF's use and management of the IPA and VSEE rotator programs, among other things. This report examines (1) the number, costs, and uses of NSF rotators for fiscal year 2008 through fiscal year 2017; (2) the strategies NSF has used to manage rotator costs and the results of these efforts; and (3) the extent to which NSF has a workforce strategy for using rotators and has evaluated the results of its rotator programs. GAO analyzed summary-level data on NSF's rotators; reviewed key documents; interviewed NSF officials; conducted semistructured interviews with a nongeneralizable sample of rotators and permanent federal employees selected from different scientific directorates within NSF; and compared NSF's management of the program to key principles for effective strategic workforce planning. The numbers of rotators—outside scientists, engineers, and educators on temporary assignment—at the National Science Foundation (NSF) and their costs in proportion to other staff remained relatively stable in fiscal years 2008 through 2017. Most rotators joined NSF under its Intergovernmental Personnel Act (IPA) mobility program. IPA rotators comprised about 12 percent of NSF's workforce and 17 percent of staff costs on average and were not subject to a federal salary cap. They remain employees of their home institutions, with NSF reimbursing the institutions for most of their salaries and benefits. The remaining rotators are considered temporary federal employees under the Visiting Scientist, Engineer, and Educator (VSEE) program; their salaries could not exceed the federal maximum for their positions. Beginning in fiscal year 2017, NSF adopted IPA rotator program cost management strategies expected to achieve the greatest savings with the least harm to recruitment, but NSF officials said it is too soon to determine the full results. For example, for new IPA rotators who had not yet begun negotiating their assignments, NSF began requiring their home institutions to pay for 10 percent of the rotators' salary and benefits. NSF officials told GAO they expect to issue a report evaluating the strategies in December 2018. NSF's IPA program steering committee recommended developing a workforce strategy for balancing the agency's use of rotators with federal staff, but as of June 2018, NSF had not developed a strategy or fully evaluated the IPA and VSEE rotator programs' results, as called for by GAO's key principles for effective strategic workforce planning. NSF officials said they recognized the value of a workforce strategy but were focusing instead on other workforce planning efforts, and they had not fully evaluated program results in part because rotators are blended into the agency's permanent workforce, making a separate evaluation difficult. Without a workforce strategy and evaluation of results, NSF is limited in its ability to manage and, if warranted, adjust its use of rotators. GAO recommends that NSF develop an agency-wide strategy for balancing the agency's use of rotators with permanent staff and evaluate the contributions of its rotator programs toward NSF's human capital goals and programmatic results. NSF agreed with GAO's recommendations.