The length of time a congressional staff member spends employed in Congress, or job tenure, is a source of recurring interest among Members of Congress, congressional staff, those who study staffing in the House and Senate, and the public. There may be interest in congressional tenure information from multiple perspectives, including assessment of how a congressional office might oversee human resources issues, how staff might approach a congressional career, and guidance for how frequently staffing changes may occur in various positions. Others might be interested in how staff are deployed, and could see staff tenure as an indication of the effectiveness or well-being of Congress as an institution. This report provides tenure data for 18 staff position titles that are typically used in Senators' offices, and information for using those data for different purposes. The positions include the following: Administrative Director Casework Supervisor Caseworker Chief Counsel Chief of Staff Communications Director Counsel Executive Assistant Field Representative Legislative Assistant Legislative Correspondent Legislative Director Office Manager Press Secretary Regional Representative Scheduler Staff Assistant State Director Publicly available information sources do not provide aggregated congressional staff tenure data in a readily retrievable or analyzable form. The most recent publicly available Senate staff compensation report, which provided some insight into the duration which congressional staff worked in a number of positions, was issued in 2006, and relied on anonymous, self-reported survey data. Data in this report are instead based on official Senate pay reports, from which tenure information arguably may be most reliably derived, and which afford the opportunity to use complete, consistently collected data. Tenure information provided in this report is based on the Senate's Report of the Secretary of the Senate , published semiannually, as collated by LegiStorm, a private entity that provides some congressional data by subscription. Senators' staff tenure data were calculated for each year between 2006 and 2016. Annual data allow for observations about the nature of staff tenure in Senators' offices over time. For each year, all staff with at least one week's service on March 31 were included. All employment pay dates from October 2, 2000, to March 24 of each reported year are included in the data. Utilizing official salary expenditure data from the Senate may provide more complete, robust findings than other methods of determining staff tenure, such as surveys; the data presented here, however, are subject to some challenges that could affect the interpretation of the information presented. Tenure information provided in this report may understate the actual time staff spend in particular positons, due in part to several features of the data. Overall, the time frame studied may lead to some underrepresentation in tenure duration. Figure 1 provides potential examples of congressional staff, identified as Jobholders A-D, in a given position. Since tenure data are not captured before October 2, 2000, some individuals, represented as Jobholder A, may have an unknown length of service prior to that date that is not captured. This feature of the data only affects a small number of employees within this dataset, since many tenure periods completely begin and end within the observed period of time, as represented by Jobholders B and C. The data last capture those who were employed in Senators' personal offices as of March 31, 2016, represented as Jobholder D, and some of those individuals likely continued to work in the same roles after that date. Data provided in this report represent an individual's consecutive time spent working in a particular position in a Senator's personal office. They do not necessarily capture the overall time worked in a Senate office or across a congressional career. If a person's job title changes, for example, from staff assistant to caseworker, the time that individual spent as a staff assistant is recorded separately from the time that individual spent as a caseworker. If a person stops working for the Senate for some time, that individual's tenure in his or her preceding position ends, although he or she may return to work in Congress at some point. No aggregate measure of individual congressional career length is provided in this report. Other data concerns arise from the variation across offices, lack of other demographic information about staff, and lack of information about where congressional staff work. Potential differences might exist in the job duties of positions with the same or similar title, and there is wide variation among the job titles used for various positions in congressional offices. The Appendix provides the number of related titles included for each job title for which tenure data are provided. Aggregation of tenure by job title rests on the assumption that staff with the same or similar title carry out the same or similar tasks. Given the wide discretion congressional employing authorities have in setting the terms and conditions of employment, there may be differences in the duties of similarly titled staff that could have effects on the interpretation of their time in a particular position. Acknowledging the imprecision inherent in congressional job titles, an older edition of the Senate Handbook states, "Throughout the Senate, individuals with the same job title perform vastly different duties." As presented here, tenure data provide no insight into the education, age, work experience, pay, full- or part-time status of staff, or other potential data that might inform explanations of why a congressional staff member might stay in a particular position. Staff could be based in Washington, DC, state offices, or both. It is unknown whether, or to what extent, the location of congressional employment might affect the duration of that employment. Tables in this section provide tenure data for selected positions in Senators' personal offices and detailed data and visualizations for each position. Table 1 provides a summary of staff tenure for selected positions since 2006. The data include job titles, average and median years of service, and grouped years of service for each positon. The "Trend" column provides information on whether the time staff stayed in a position increased, was unchanged, or decreased between 2006 and 2016. Table 2 - Table 19 provide information on individual job titles over the same period. In all of the data tables, the average and the median length of tenure columns provide two different measures of central tendency, and each may be useful for some purposes and less suitable for others. The average represents the sum of the observed years of tenure, divided by the number of staff in that position. It is a common measure that can be understood as a representation of how long an individual remains, on average, in a job position. The average can be affected disproportionately by unusually low or high observations. A few individuals who remain for many years in a position, for example, may draw the average tenure length up for that position. A number of staff who stay in a position for only a brief period may depress the average length of tenure. Another common measure of central tendency, the median, represents the middle value when all the observations are arranged by order of magnitude. The median can be understood as a representation of a center point at which half of the observations fall below, and half above. Extremely high or low observations may have less of an impact on the median. Generalizations about staff tenure are limited in at least three potentially significant ways, including: the relatively brief period of time for which reliable, largely inclusive data are available in a readily analyzable form; how the unique nature of congressional work settings might affect staff tenure; and the lack of demographic information about staff for which tenure data are available. Considering tenure in isolation from demographic characteristics of the congressional workforce might limit the extent to which tenure information can be assessed. Additional data on congressional staff regarding age, education, and other elements would be needed for this type of analysis, and are not readily available at the position level. Finally, since each Senator's office serves as its own hiring authority, variations from office to office, which for each position may include differences in job duties, work schedules, office emphases, and other factors, may limit the extent to which aggregated data provided here might match tenure in a particular office. Despite these caveats, a few broad observations can be made about staff in Senators' offices. Between 2006 and 2016, staff tenure, based on the trend of the median number of years in the position, appears to have increased by six months or more for staff in 10 position titles in Senate offices. The median tenure was unchanged for eight positions. This may be consistent with overall workforce trends in the United States. Although pay is not the only factor that might affect an individual's decision to remain in or leave a particular job, staff in positions that generally pay less typically remained in those roles for shorter periods of time than those in higher-paying positions. Some of these lower-paying positions may also be considered entry-level positions in some Senators' offices; if so, Senate office employees in those roles appear to follow national trends for others in entry-level types of jobs, remaining in the role for a relatively short period of time. Similarly, those in more senior positions, which often require a particular level of congressional or other professional experience, typically remained in those roles comparatively longer, similar to those in more senior positions in the general workforce. There is wide variation among the job titles used for various positions in congressional offices. Between October 2000 and March 2016, House and Senate pay data provided 13,271 unique titles under which staff received pay. Of those, 1,884 were extracted and categorized into one of 33 job titles used in CRS Reports about Member or committee offices. Office type was sometimes related to the job titles used. Some titles were specific to Member (e.g., District Director, State Director, and Field Representative) or committee (positions that are identified by majority, minority, or party standing, and Chief Clerk) offices, while others were identified in each setting (Counsel, Scheduler, Staff Assistant, and Legislative Assistant). Other job titles variations reflect factors specific to particular offices, since each office functions as its own hiring authority. Some of the titles may distinguish between roles and duties carried out in the office (e.g., chief of staff, legislative assistant, etc.). Some offices may use job titles to indicate degrees of seniority. Others might represent arguably inconsequential variations in title between two staff members who might be carrying out essentially similar activities. Examples include: Seemingly related job titles, such as Administrative Director and Administrative Manager, or Caseworker and Constituent Advocate Job titles modified by location, such as Washington, DC, State, or District Chief of Staff Job titles modified by policy or subject area, such as Domestic Policy Counsel, Energy Counsel, or Counsel for Constituent Services Committee job titles modified by party or committee subdivision. This could include a party-related distinction, such as a Majority, Minority, Democratic, or Republican Professional Staff Member. It could also denote Full Committee Staff Member, Subcommittee Staff Member, or work on behalf of an individual committee leader, like the chair or ranking member. The titles used in this report were used by most Senators' offices, but a number of apparently related variations are included to ensure inclusion of additional offices and staff. Table A-1 provides the number of related titles included for each position used in this report or related CRS Reports on staff tenure. A list of all titles included by category is available to congressional offices upon request.

Summary:
The length of time a congressional staff member spends employed in a particular position in Congress--or congressional staff tenure--is a source of recurring interest to Members, staff, and the public. A congressional office, for example, may seek this information to assess its human resources capabilities, or for guidance in how frequently staffing changes might be expected for various positions. Congressional staff may seek this type of information to evaluate and approach their own individual career trajectories. This report presents a number of statistical measures regarding the length of time Senate office staff stay in particular job positions. It is designed to facilitate the consideration of tenure from a number of perspectives. This report provides tenure data for a selection of 18 staff position titles that are typically used in Senators' offices, and information on how to use those data for different purposes. The positions include Administrative Director, Casework Supervisor, Caseworker, Chief Counsel, Chief of Staff, Communications Director, Counsel, Executive Assistant, Field Representative, Legislative Assistant, Legislative Correspondent, Legislative Director, Office Manager, Press Secretary, Regional Representative, Scheduler, Staff Assistant, and State Director. Senators' staff tenure data were calculated as of March 31, for each year between 2006 and 2016, for all staff in each position. An overview table provides staff tenure for selected positions for 2016, including summary statistics and information on whether the time staff stayed in a position increased, was unchanged, or decreased between 2006 and 2016. Other tables provide detailed tenure data and visualizations for each position title. Between 2006 and 2016, staff tenure appears to have increased by six months or more for staff in 10 position titles in Senators' offices, based on the trend of the median number of years in the position. For eight positions, the median tenure trend was unchanged. These findings may be consistent with overall workforce trends in the United States. Pay may be one of many factors that affect an individual's decision to remain in or leave a particular job. Senate office staff holding positions that are generally lower-paid typically remained in those roles for shorter periods of time than those in generally higher-paying positions. Lower-paying positions may also be considered entry-level roles; if so, tenure for Senators' office employees in these roles appears to follow national trends for other entry-level jobs, which individuals hold for a relatively short period of time. Those in more senior positions, where a particular level of congressional or other professional experience is often required, typically remained in those roles comparatively longer, similar to those in more senior positions in the general workforce. Generalizations about staff tenure are limited in some ways, because each Senator's office serves as its own hiring authority. Variations from office to office, which might include differences in job duties, work schedules, office emphases, and other factors, may limit the extent to which data provided here might match tenure in another office. Direct comparisons of congressional employment to the general labor market may have similar limitations. An employing Senator's retirement or electoral loss, for example, may cause staff tenure periods to end abruptly and unexpectedly. This report is one of a number of CRS products on congressional staff. Others include CRS Report R43946, Senate Staff Levels in Member, Committee, Leadership, and Other Offices, 1977-2016, and CRS Report R44324, Staff Pay Levels for Selected Positions in Senators' Offices, FY2001-FY2014.