The Prison Rape Elimination Act of 2003 (P.L. 108-79) requires the Bureau of Justice Statistics (BJS) to carry out a comprehensive statistical review and analysis of the incidence and effects of prison rape for each calendar year.
A multi-stage stratified systematic probability-proportional-to-size (PPS) sample design was used to select a random sample of over 250 parole (field or district) offices across the United States, followed by a random sample of parolees supervised at those offices.
The parole office sampling frames were developed using the 2006 Census of Parole Offices conducted by the United States Census Bureau on behalf of BJS. The original frame consisted of two sub-frames: a field office group (FOG) level frame of 800 field office groups and a district level frame of 101 district (or regional administrative) offices. Parole field offices were not included in the office sampling frame if they: (1) were administrative offices that did not actively supervise parolees, (2) were specialty offices (e.g., those supervising only sex offenders or only individuals committed to treatment/confinement facilities), (3) were located in difficult to reach geographic regions, (4) had a population of less than 40 and could not be combined with another office within 75 miles for sampling purposes. A separate frame for district offices was created because field offices within these districts (or regions) were not enumerated in the 2006 census. All district offices were included in this frame, with the intent of specifying and enumerating all field offices under their authority once selected. Field offices within these districts, once specified, were subject to the same criteria as the field office frame, with the exception that field offices were grouped if within 120 miles.
Each of these sub-frames was sampled from separately to produce the final sample. A two-stage stratified systematic PPS sample design was used for selection from the office sub-frame, while a three-stage design was used for the district sub-frame.
Field Office Groups (FOGs) were selected from the field office frame using PPS sampling procedure. A total of 151 FOGs (seven involving combined offices) were selected from the office sampling frame. At the time of sample selection, an additional 37 reserve offices were selected. The first 10 reserve offices on the list were eventually activated. The first four offices were activated as a result of four sampled offices having no eligible respondents supervised at those sites. The remaining sites were activated to offset the possibility of refusals in states for which approvals were slow to materialize; however, those activated were not eventually required for replacement and served only to enhance the sample size.
District offices were selected from the district office sub-frame using PPS sampling procedures. A total of 50 districts were selected for inclusion. Following selection of districts, project staff contacted states requesting an enumeration of field offices and office sizes within each selected district. Offices with less than 40 parolees were eliminated if there was no other office within 120 miles for grouping. FOGs within each district sampled were then sampled using PPS sampling procedures. A total of 71 FOGs were selected from these districts (21 involving combined offices) after enumeration of offices within the selected districts. An additional twenty reserve districts were selected from this frame. Eleven of the first twelve districts on the reserve list were activated. One was activated as a result of a sampled district having no eligible supervised parolees. The remaining districts were activated to offset the possible loss of states for which access was difficult to obtain. However, because approval was eventually obtained for all sampled states, the extra reserve districts were not required for replacement and served only to enhance the sample size. Once enumerated and selected, all chosen offices (or FOGs) agreed to participate, except one, and another office was randomly selected from the same district.
After approvals from states and offices were received, a roster of eligible former prisoners was requested from each parole office within each FOG to be developed at approximately two and half to three weeks prior to scheduled interviewing period at the office. Eligible former prisoners were defined as:
Individuals who are under active supervision by the parole office (on the day of roster preparation) after being released from state prison and were 18 years of age or older. Individuals who had absconded, were re-incarcerated or committed, were in a half way house or community treatment center, had a warrant issued for arrest, were in violator status, or had been transferred to another parole office were ineligible.
A sample of eligible former prisoners was randomly selected from these rosters for inclusion in the study.
The target sample size was 260 (196 males; 64 females) for the larger offices and 130 (98 males; 32 females) for the smaller offices. Female former prisoners were sampled at a higher rate than males to insure that sufficient numbers were included to provide precise estimates at the national level. For sites with a roster population of 130 or less; all eligible respondents on the roster were selected to participate in the survey. In total, 34,782 former prisoners were selected to participate in the study.
All individuals who were under active supervision by state parole offices (on the day of roster preparation) after being released from state prison, were 18 years of age or older, and were not re-incarcerated, absconded, in a half way house or community treatment center, did not have warrants issued for arrest, were not in violator status, and/or had not been transferred to other parole offices. All state parole offices were eligible for selection except those excluded due to uniqueness of supervision type, or due to geographic and/or size limitations (please see sampling description).
Due to the possibility of individual disclosure, all interviews from offices participating in the pre-test were eliminated from the final data file prepared for ICPSR. Because of multiple changes in the data instrument after the pre-test, the risk of identification of participating offices and individual respondents in the pre-test was determined to be too great.
Individuals who were under active supervision by the parole office (on the day of roster preparation) after being released from state prison; were 18 years of age or older; were not re-incarcerated, absconded, in a half way house or community treatment center; had not been transferred to other parole offices; did not have warrants issued for arrest; and were not in violator status.
After the elimination of ineligible cases, the overall response rate was 60.6 percent.