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Beware of "Average Length of Stay!"
 
 

Most jails operate two distinct functions: a short-term lockup where inmates are temporarily detained before they are released, and a longer-term detention and corrections facility. Although national statistics are not available, it is likely that the average jail releases more than 75% of its inmates within 72 hours.

The short-term pre-arraignment detainees who comprise the vast majority of the inmates who enter our jails, account for a very small proportion of the jail beds on a given day. It is not unusual to find that these 72-hour-or-less inmates occupy under 5% of the beds.

This dynamic—lots of short-term detainees (measured in hours) dominating the admissions but occupying very few beds—often results in serious misconceptions about the jail population by the public. When we talk about “average length of stay“ for a jail inmate, we are describing the jail population based on admissions but we are seriousness of the inmate population.

While analyzing inmate length of stay may be an important tool for managers and policymakers, it should always be tempered by an understanding of the dynamics of the jail. In many jurisdictions, this is accomplished by describing inmate population dynamics in terms of both admissions and detention days (number of days spent.)

The following chart is an good example of the way the admissions, detention days, and length of stay may be combined to provide a three-dimension view of the dynamics of the jail population.


 
     
 
Reason for Release from Jail (July 2001 - June 2004)
Release Code
# of Admits
% Admissions
Detention Days
% Detention Days
Avg. # Beds
ALOS
Released to State Department of Corrections
939
3.32%
129,876
31.73%
89.0
138.31
Served Sentence
6,161
21.80%
71,236
17.41%
48.8
11.56
Released to Other Agency
1,355
4.79%
66,500
16.25%
45.4
49.08
Transferred to State Facility other than prison
337
1.19%
35,754
8.74%
24.5
106.09
Surety Bond
13,634
48.24%
35,719
8.73%
24.5
2.62
Released on Probation
321
1.14%
15,386
3.76%
10.5
47.93
PR Bond (Personal Recognizance)
334
1.18%
9,332
2.28%
6.4
27.94
Charges Dismissed
189
0.67%
7,856
1.92%
5.4
41.57
Transferred to Parole Violator Programy
112
0.40%
7,793
1.90%
5.3
69.58
Transferred to Substance Abuse  Facility
98
0.35%
6,957
1.70%
4.8
70.99
Released by Order of Judge
426
1.51%
5,621
1.37%
3.9
13.19
Bond Posted by Attorney 
557
1.97%
4,871
1.19%
3.3
8.75
Released to Immigration and Nat. Service
65
0.23%
4,440
1.08%
3.0
68.31
Paid Cash Bond
957
3.39%
2,004
0.49%
1.4
2.09
Paid Fine
2,618
9.26%
1,914
0.47%
1.3
0.73
Subtotal Avg. # Beds
277.5
 
     
  The first line of the table above is a classic example. Although less than 4% of the inmates admitted to this jail are released to the State department of corrections, these inmates accounted for nearly 342% of the detention days. Put another way, on an average day, 34% of the inmates who were in this jail would eventually be released to the department of corrections. For this inmate group, the average length of stay was 89 days, compared to 1.3 days for inmates were released after paying fines (at the bottom of the table.)

The following text is drawn from a recent county jail study, and is provided as a sample of how the combination of admissions and detention days yields a useful and accurate analysis of the jail population.
 
     
  Finding Points of Intervention  
 

XXX County officials should be proactive in their efforts to manage, and hopefully decrease, the rate of growth of future jail populations.  Finding effective points of intervention requires a further review of the data.

As the previous chapters of this report suggest, the dramatic increase in the jail population growth can be attributed in part to the length of stay for jail inmates.  Figure 1 underscores the impact of inmate length of stay in the past three years.

 
Slide1.jpeg

As the chart demonstrates, admissions to the XXX County Jail increased by less than 1 percent in the past three years, while the number of inmate detention days increased by nearly 28 percent.  The length of stay for inmates clearly is responsible for the increase.

As we reported earlier, nearly half of the inmates admitted to the XXX County Jail spend less than one day in confinement, but most of the jail beds are used by inmates who spend 30 or more days in confinement.  This is depicted in Figure 2.

 

FIGURE 2
Admissions v. Detention Days (4 Year Dataset)

 

Percent of Admissions

% Detention Days (Beds Used)

< 1 days

47.0%

0.0%

1 day

17.5%

1.2%

2 days

8.9%

1.2%

3 days

2.7%

0.6%

4 days

1.8%

0.5%

5 days

1.3%

0.5%

6-10

3.5%

1.8%

11-30

5.3%

7.2%

31-60

4.3%

13.2%

61-90

2.5%

13.1%

91-120

1.8%

12.8%

121-150

1.0%

9.5%

151-180

0.7%

8.5%

181-365

1.5%

24.7%

366-548

0.1%

3.9%

549+

0.0%

1.4%

Figure 3 shows that 76.1 percent of all inmates are released within three days, but they account for only 3.0 percent of the jail beds.  Conversely, 3.4 percent of the inmates spend more than 90 days in jail, but they account for 47.9 percent of the jail beds.

FIGURE 3
Cumulative Percentage of Admissions v. Detention Days 

Cumulative Percent of Admissions

Cumulative Percent of Detention Days

< 1 days

47.0%

0.0%

1 day

64.5%

1.2%

2 days

73.4%

2.4%

3 days

76.1%

3.0%

4 days

77.9%

3.5%

5 days

79.2%

3.9%

6-10

82.7%

5.8%

11-30

88.0%

12.9%

31-60

92.3%

26.1%

61-90

94.8%

39.2%

91-120

96.6%

52.1%

121-150

97.6%

61.6%

151-180

98.4%

70.0%

181-365

99.8%

94.7%

366-548

100.0%

98.6%

549+

100.0%

100.0%

 Figure 4 provides a graphic portrayal of how the length of stay drops off in the first hours after admission to the jail.

FIGURE 4
Percent of Inmates Remaining In Jail by Days

Slide2

Figure 5 provides another view of length of stay, depicting the small proportion of beds that are used by the inmates who are confined for short periods of time.

FIGURE 5
Percent of Beds Used by Inmate Length of Stay

Slide3

Inmates who spend less than 11 days in confinement account for only 5.*% of the beds used, but represent 82.7 percent of the admissions. Figure 6 provides a breakdown of the very short-term inmates for the calendar year 2004.

FIGURE 6
Length of Stay by Hours (3 days and Less), Calendar Year 2004

Hours Spent

Number of Admissions

Percent Admissions

Cumulative Percent Admissions

0

2

0.03%

0.03%

1

399

5.15%

5.18%

2

390

5.04%

10.22%

3

206

2.66%

12.88%

4-6

302

3.90%

16.78%

7-9

209

2.70%

19.48%

10-12

254

3.28%

22.76%

13-15

292

3.77%

26.53%

16-18

165

2.13%

28.66%

19-21

188

2.43%

31.09%

22-24

167

2.16%

33.25%

25-36

1,083

13.99%

47.24%

37-48

653

8.43%

55.67%

49-60

254

3.28%

58.95%

61-72

199

2.57%

61.52%

73+

2,979

38.48%

100.00%

Figure 6 shows that 61.5 percent of all inmates admitted in 2004 were released from jail within 72 hours of admission, and 33.3 percent were released within 24 hours.  This analysis is useful during the planning and design process, as it provides insights into the need for short-term detention.  In particular, it is relevant to planning an expanded or new intake and booking area, which would resemble a large processing center that could hold and manage new admissions for up to eight hours and facilitate releases, if appropriate, prior to being placed in a jail cell.

A further examination of the length of stay by year helps to focus on the specific areas of growth.  Figure 7 shows the changes in length of stay in the past four years.

FIGURE 7
Percent of Detention Days by Length of Stay, 7/2000 – 6/2004

 

Percent of Detention Days

Length of Stay

2000-01

2001-02

2002-03

2003-04

< I day

0.00%

0.00%

0.00%

0.00%

1 day

1.13%

1.40%

1.34%

0.99%

2 days

0.86%

1.36%

1.26%

1.39%

3 days

0.39%

0.55%

0.58%

0.66%

4 days

0.40%

0.39%

0.59%

0.61%

5 days

0.33%

0.37%

0.47%

0.59%

6-10

1.23%

1.80%

1.87%

2.14%

11-30

5.46%

6.18%

8.63%

7.68%

31-60

9.11%

12.31%

14.93%

15.33%

61-90

7.12%

13.62%

14.24%

16.73%

91-120

8.62%

14.19%

12.40%

15.99%

121-150

8.74%

10.16%

8.96%

9.72%

151-180

9.14%

8.57%

7.60%

8.61%

181-365

39.55%

21.95%

20.81%

17.81%

366-548

6.71%

3.78%

4.43%

1.01%

549+

1.23%

3.38%

1.90%

0.73%

While the number of beds occupied by inmates who spent over 180 days dropped substantially after 2000-01, the beds used by inmates who spent between 31 and 120 days in confinement increased by 93.3 percent.