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Rick Scott, Governor
Florida Department of Corrections, Secretary Michael D. Crews

Florida Department of Corrections
Michael D. Crews, Secretary

Results: Adult Males

Table 4 presents the base recidivism rates using the re-offense measure generated from the SAS© lifetest procedure described earlier with follow-up periods of six months to sixty months. These data show that, in the short term through an eighteen months follow-up period, the re-offense rates of public and private adult male inmates are virtually identical within all six of the outcome measures. In the longer follow-up periods of thirty-six months and sixty months, private adult male inmates have higher re-offense rates within four of the six groups (A1, B1, B2, and B3) and are the same as the public adult male inmates in the A2 and C1 groups. However, none of these re-offense rate differences are statistically significant at the p<.05 level.

Table 4: Adult Males - Re-Offense Recidivism Rates with No Controls for Explanatory Variables
Treatment Effect Measurement Group

  A1 Group A2 Group B1 Group B2 Group B3 Group C1 Group
Public Private Public Private Public Private Public Private Public Private Public Private
Number of Cases
48,744
3,553
38,583
2,793
58,342
2,993
65,483
3,176
66,199
3,306
71,276
3,562
Follow-Up Period
 
 
 
 
 
 
 
 
 
 
 
 
6 Months
13.3%
12.7%
13.3%
12.6%
12.3%
11.9%
12.3%
12.0%
12.3%
12.0%
12.5%
12.2%
12 Months
22.6%
22.3%
22.5%
22.1%
21.0%
21.5%
21.0%
21.6%
21.1%
21.4%
21.4%
21.3%
18 Months
29.4%
29.3%
29.2%
28.8%
27.5%
28.7%
27.6%
28.6%
27.7%
28.4%
28.1%
27.7%
24 Months
34.4%
34.9%
34.1%
34.5%
32.3%
34.6%
32.5%
34.4%
32.5%
34.2%
33.0%
33.1%
36 Months
41.9%
45.1%
41.7%
41.6%
39.4%
42.3%
39.7%
42.1%
39.7%
42.1%
40.3%
40.4%
48 Months
46.8%
48.2%
46.4%
47.9%
44.1%
47.9%
44.4%
47.8%
44.4%
47.7%
45.2%
46.5%
60 Months
49.9%
51.3%
49.5%
51.1%*
47.3%
50.9%
47.7%
50.7%
47.7%
50.7%
48.4%
49.8%
None of the recidivism rate differences were statistically significant at the p<.05 level (Wilcoxon Test).
* 59 months.

Re-imprisonment rates are displayed in Table 5, prior to controlling for relevant factors, for the public and private adult male releases within each of the six methods of identifying the two types of inmates. Overall, public adult male inmates have slightly higher re-imprisonment rates; however, only four of the possible thirty-six differences are higher than 2.0% (Groups A2 and C1 for thirty-six months, Group A2 for 48 months, and Group A1 for 56 months) and none are over 3.0%. Additionally, none of these re-imprisonment rate differences between public and private adult male inmates are statistically significant at the p<.05 level.

Table 5: Adult Males: Re-Imprisonment Recidivism Rates with No Controls for Explanatory Variables
Treatment Effect Measurement Group

  A1 Group A2 Group B1 Group B2 Group B3 Group C1 Group
Public Private Public Private Public Private Public Private Public Private Public Private
Number of Cases
48,744
3,553
38,583
2,793
58,342
2,993
65,483
3,176
66,199
3,306
71,276
3,562
Follow-Up Period
 
 
 
 
 
 
 
 
 
 
 
 
6 Months
10.1%
9.8%
10.9%
9.7%
9.1%
8.6%
9.1%
8.6%
9.2%
8.6%
9.3%
8.9%
12 Months
16.9%
16.2%
17.2%
15.9%
15.5%
14.8%
15.6%
14.8%
15.6%
14.9%
15.7%
14.8%
18 Months
21.6%
20.9%
22.1%
20.6%
20.0%
19.4%
20.2%
19.3%
20.2%
19.2%
20.4%
18.8%
24 Months
25.0%
24.2%
25.2%
23.5%
23.1%
23.0%
23.4%
22.8%
23.4%
22.7%
23.7%
21.9%
36 Months
29.8%
28.2%
30.4%
27.5%
27.7%
27.3%
28.0%
26.9%
27.9%
26.9%
28.3%
25.8%
48 Months
32.4%
30.2%
32.9%
29.8%
30.1%
29.0%
30.4%
28.7%
30.3%
28.6%
30.7%
27.7%
60 Months
33.2%*
30.8%*
n/a
n/a
30.8%*
29.7%*
31.2%*
29.3%*
31.1%*
29.3%*
n/a
n/a
None of the recidivism rate differences were statistically significant at the p<.05 level (Wilcoxon Test).
* No comparison group had estimates for longer than 56 months.

Table 6 displays the distributions of the private and public adult male inmates on the eighteen variables used in the final survival models to answer the question whether recidivism rates differ between the two groups. The demographic characteristics of age at release, race, and ethnicity, across the public and private adult male inmates are virtually the same. In contrast, public adult male inmates are somewhat more likely to have more prior recidivism events than private inmates (average: public = 1.2; private = 1.1) and are considerably more likely to be released as close custody inmates (public = 17.0%; private = 1.1%). Public adult male inmates are also much more likely to spend longer lengths of time in prison (average months: public = 31.3; private = 16.8) and have more disciplinary problems while in prison (average disciplinary reports: public = 2.9; private = 0.8). The median TABE score for public adult male inmates is slightly lower than for private adult male inmates (7.1 versus 7.6) and they are considerably more likely to be released to some form of post-prison supervision (36.9% versus 23.4%). In terms of their most serious crime type, public adult male inmates are more likely to have committed a homicide, sex/lewd offense, or a robbery than private inmates. However, the two groups are very similar in terms of their total number of convictions for property, drug, and weapons offenses.

Table 6: Adult Males - Descriptive Statistics of Public and Private Inmates
Treatment and Control Group Definition B1
  Public Private Total
Total Cases
58,342
2,993
61,335
Age at Release
Under 18
10
0.0%
0
0.0%
10
18 to 24
7,934
13.6%
387
12.9%
8,321
25 to 34
24,697
42.3%
1,270
42.4%
25,967
35 to 49
22,940
39.3%
1,173
39.2%
24,113
50 to 59
2,211
3.8%
138
4.6%
2,349
60+
550
0.9%
25
0.8%
575
Average
34.0
34.2
 
Race – Black
33,891
58.1%
1,753
58.6%
35,644
Hispanic
2,995
5.1%
161
5.4%
3,156
Prior Recidivism Events **
0
25,404
43.5%
1,425
47.6%
26,829
1
14,554
24.9%
688
23.0%
15,242
2
8,702
14.9%
424
14.2%
9,126
3
5,224
9.0%
240
8.0%
5,464
4
2,676
4.6%
125
4.2%
2,801
5 +
1,782
3.1%
91
3.0%
1,873
Average
1.2
1.1
 
Custody Low **
28,206
48.3%
1,744
58.3%
29,950
Custody High **
9,944
17.0%
33
1.1%
9,977
Months in Prison **
1-12
15,193
26.0%
1,455
48.6%
16,648
13-24
16,737
28.7%
1,004
33.5%
17,741
25-36
9,452
16.2%
323
10.8%
9,775
37-48
5,781
9.9%
116
3.9%
5,897
49-60
3,556
6.1%
55
1.8%
3,611
61+
7,623
13.1%
40
1.3%
7,663
Average
31.3
16.8
 
Total Disciplinary Reports **
0
28,491
48.8%
2,139
71.5%
30,630
1
9,896
17.0%
458
15.3%
10,354
2
5,129
8.8%
169
5.6%
5,298
3 to 6
7,703
13.2%
158
5.3%
7,861
7 or More
7,123
12.2%
69
2.3%
7,192
Average
2.9
0.8
 
Last TABE Score **
1-3.9
11,110
19.0%
489
16.3%
11,599
4-8.9
30,535
52.3%
1,484
49.6%
32,019
9-11.9
9,215
15.8%
603
20.1%
9,818
12-12.9
7,482
12.8%
417
13.9%
7,899
Median
7.1
7.6
 
Supervision – Yes **
21,541
36.9%
699
23.4%
22,240
Most Serious – Homicide **
3,016
5.2%
50
1.7%
3,066
Most Serious - Sex/Lewd **
5,247
9.0%
179
6.0%
5,426
Most Serious – Robbery **
12,122
20.8%
456
15.2%
12,578
Most Serious - Other Violent
14,857
25.5%
806
26.9%
15,663
Most Serious – Burglary *
11,723
20.1%
653
21.8%
12,376
Total Property Crimes (Average)
1.1
1.1
 
Total Drug Crimes (Average) **
1.1
1.4
 
Total Weapons Crimes (Average)
0.2
0.2
 

Significance levels based on T-Tests when averages are displayed and Chi-Square when they are not.
* Significant at p<.05, ** Significant at p<.01.

The differences described on many of the control variables for the public and private adult male inmates clearly indicates the need to hold these factors constant when evaluating whether differences in recidivism probabilities exist between the two groups. Public adult male inmates have higher rates of prior recidivism rates, close custody, and disciplinary infractions, as well as lower TABE scores. These characteristics are all associated with a higher likelihood of recidivism. In contrast, private adult male inmates have shorter lengths of stay in prison and are less likely to have post-prison supervision, which are predictive of higher recidivism rates.

To determine whether the private prison experience for adult males affects their likelihood of recidivism in terms of re-offense or re-imprisonment rates, we employed multivariate survival models which control, or hold constant, the effects of other variables known to influence recidivism rates. Table 7 displays these results and clearly shows there are no statistically significant differences in re-offense or re-imprisonment rates between public and private adult male inmates using any of six methods for quantifying private prison experience. Using the re-offense recidivism measure, all the relationships between the type of prison and reoffense indicate that private inmates are slightly more likely to recidivate than public adult male inmates (MLE’s = .01 to .04) but these differences are not statistically significant. Using the reimprisonment recidivism measure, all the relationships between the type of prison and this recidivism measure are very slight (-.01 to +.01) and, again, not statistically significant.

Table 7: Adult Males - Recidivism Predictor Variables Using Survival Analysis
Maximum Likelihood Estimates (MLE’s)
  Re-Offense Re-Imprisonment
Effect Measure A1 A2 B1 B2 B3 C1 A1 A2 B1 B2 B3 C1
Total Cases
52,297
41,376
61,335
68,659
69,505
74,838
52,297
41,376
61,335
68,659
69,505
74,838
Treatment (Private) Cases
3,553
2,793
2,993
3,176
3,306
3,562
3,553
2,793
2,993
3,176
3,306
3,562
Control (Public) Cases
48,744
38,583
58,342
65,483
66,199
71,276
48,744
38,583
58,342
65,483
66,199
71,276
Treatment (Private) Group
.03
.01
.04
.03
.04
.01
.01
.00
-.01
-.01
-.01
.01
Age at Release
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
Black
.21**
.22**
.20**
.20**
.22**
.22**
.24**
.23**
.23**
.23**
.24**
.25**
Hispanic
-.02
-.01
-.05
-.04
-.05
-.06
-.03
-.04
-.05
-.02
-.04
-.05
Prior Recidivism
.22**
.22**
.22**
.22**
.22**
.22**
.28**
.27**
.29**
.29**
.29**
.29**
Custody - Low
-.11**
-.10**
-.13**
-.14**
-.15**
-.15**
-.15**
-.16**
-.16**
-.17**
-.18**
-.18**
Custody - High
.04*
.05*
.02
.02
.03
.03
.06*
.06*
.04
.04
.05*
.06*
Months in Prison
-.01**
-.01**
-.01**
-.01**
-.01**
-.01**
-.00**
-.00**
-.00**
-.00**
-.00**
-.00**

Total Disciplinary Reports

.02**
.02**
.02**
.02**
.02**
.02**
.01**
.01**
.02**
.02**
.02**
.02**
Last TABE grade
-.02**
-.02**
-.02**
-.02**
-.02**
-.02**
-.03**
-.03**
-.03**
-.03**
-.03**
-.03**
Supervision
-.15**
-.16**
-.15**
-.14**
-.15**
-.15**
.04
.03
.05**
.06**
.06**
.07**
Most Serious - Homicide
-.29**
-.28**
-.26**
-.28**
-.28**
-.28**
-.19**
-.21**
-.14**
-.18**
-.19**
-.22**
Most Serious - Sex/Lewd
-.37**
-.36**
-.31**
-.32**
-.32**
-.35**
-.24**
-.27**
-.14**
-.17**
-.16**
-.20**
Most Serious - Robbery
.01
.02
.07**
.06**
.05*
.01
.14**
.13**
.23**
.21**
.20**
.16**
Most Serious - Other Violent
-.01
.00
.02
.01
.01
-.02
.05
.05
-.12**
-.09**
-.09**
.05
Most Serious - Burglary
.11**
.13**
.16**
.16**
.15**
.12**
.23**
.23**
.30**
.31**
.29**
.27**
Total Property Crimes
.03**
.03**
.03**
.03**
.03**
.03**
.03**
.02**
.03**
.02**
.02**
.03**
Total Drug Crimes
.03**
.03**
.03**
.03**
.03**
.03**
.02**
.02**
.02**
.02**
.02**
.02**
Total Weapons Crimes
-.02
-.02
-.01
-.02
-.02*
-.02*
-.03*
-.02
-.03
-.04**
-.04**
-.04**
* Significant at p<.05
** Significant at p<.01.