projecting state prison populations: an ncrp innovationan ncrp innovation april 5, 2017 authors:...

Copyright © 2016, Abt Associates Inc.

Projecting State

Prison Populations:

An NCRP InnovationApril 5, 2017

Authors: Christopher Cutler, William

Rhodes, Gerry Gaes

Disclaimer: The analyses and conclusions presented

here are those of the authors and do not necessarily

represent the views and opinions of the Bureau of

Justice Statistics or the U.S. Department of Justice.

Abt Associates | pg 2


Acknowledgment

This work was supported by Grant No. 2015-R2-CX-

K135 awarded by the Bureau of Justice Statistics,

Office of Justice Programs, U.S. Department of Justice

to Abt Associates. Points of view in this presentation

are those of the presenters and do not represent the

official position of the U.S. Department of Justice.



Presentation Roadmap

Methodology

Examples

Feedback




Methodology

Examples

Feedback



Prison Population Projections

Generate 1 - 5 year prison stock and

admission projections

Data requirements – 5+ years of data in

NCRP

Full methodology available on ncrp.info



Methodology Flow Chart

Goal: 2020 Stock Estimate





2 Components

Admissions after 2015

Stock in 2015





2 Components


Stock in 2015

Regress time since admission on 2011-2015

admissions





2 Components


Stock in 2015


admissions

Flow-based Estimate





2 Components


Stock in 2015

Regress offense type and % sentence served on the

stock in 2010





2 Components


Stock in 2015

Stock-based Estimate


stock in 2010





2 Components


Stock in 2015


admissions

Flow-based Estimate

Stock-based Estimate


stock in 2010



Subpopulation Estimation

Group similar offenders to better observe

trends

Offenders grouped by:

– Offense seriousness

– Observed incarceration history



Prediction Strata

Offense Seriousness

1(Least)

2 3 4 5 6 7(Most)

8(Drug)

Inca

rce

rati

on

His

tory 0

1

2

3



Offense Seriousness

Related to time served and sentence length

More serious offense --> longer period of

incarceration



Offense Seriousness

Seven groups (1 – least serious; 7 most

serious)

– First 3 groups - ~20 % of admissions each

– Last 4 groups - ~10 % of admissions each

Drug offenses treated as separate group

– Eighth group



Offense Seriousness Categories

2000 – 2015 AZ Admissions



Offense Seriousness Categories

2015 AZ Stock



Incarceration History

Recency of prior prison stay approximates

offender risk score



Incarceration History

Years Since Previous Prison Release

0 1 2 3 4 5 6 7

No Prior Incarcerations

0 1 2 3



Flow-based Assumptions

Trends in admissions and releases continue

into future

Time served for new admissions is consistent

with observed time served for admissions in

2011 – 2015



Stock-based Assumptions

Proportion of 2010 stock remaining in 2015

stock is the same as the proportion of 2015

stock remaining in 2020 stock



Additional Considerations

Some shifts in policy are important for

projections

Adjustment factors allow for modification with

outside information




Methodology

Examples

Feedback




Methodology

Examples

AZ Admission Projections

Feedback




Offense Seriousness Category 2015 2016 2017 2018 2019 2020

(Least serious) 1 1,791 1,739 1,626 1,501 1,388 1,343

2 1,815 1,767 1,751 1,718 1,685 1,658

3 2,740 2,782 2,794 2,790 2,780 2,770

4 2,188 2,084 2,087 2,092 2,086 2,078

5 912 945 960 982 1,005 1,022

6 1,772 1,866 1,911 1,937 1,962 1,986

(Most Serious) 7 1,866 1,867 1,860 1,855 1,839 1,824

(Drug Offenses) 8 6,947 7,275 7,474 7,628 7,759 7,871

Total 20,031 20,325 20,464 20,504 20,504 20,553

Change from 2015 1.5% 2.2% 2.4% 2.4% 2.6%





(Least serious) 1 1,791 1,739 1,626 1,501 1,388 1,343

2 1,815 1,767 1,751 1,718 1,685 1,658

3 2,740 2,782 2,794 2,790 2,780 2,770

4 2,188 2,084 2,087 2,092 2,086 2,078

5 912 945 960 982 1,005 1,022

6 1,772 1,866 1,911 1,937 1,962 1,986

(Most Serious) 7 1,866 1,867 1,860 1,855 1,839 1,824

Total 20,031 20,325 20,464 20,504 20,504 20,553

Change from 2015 1.5% 2.2% 2.4% 2.4% 2.6%

Admissions Decreasing





(Least serious) 1 1,791 1,739 1,626 1,501 1,388 1,343

2 1,815 1,767 1,751 1,718 1,685 1,658

3 2,740 2,782 2,794 2,790 2,780 2,770

4 2,188 2,084 2,087 2,092 2,086 2,078

5 912 945 960 982 1,005 1,022

6 1,772 1,866 1,911 1,937 1,962 1,986

(Most Serious) 7 1,866 1,867 1,860 1,855 1,839 1,824

(Drug Offenses) 8 6,947 7,275 7,474 7,628 7,759 7,871

Total 20,031 20,325 20,464 20,504 20,504 20,553

Change from 2015 1.5% 2.2% 2.4% 2.4% 2.6%

Admissions Increasing





(Least serious) 1 1,791 1,739 1,626 1,501 1,388 1,343

2 1,815 1,767 1,751 1,718 1,685 1,658

3 2,740 2,782 2,794 2,790 2,780 2,770

4 2,188 2,084 2,087 2,092 2,086 2,078

5 912 945 960 982 1,005 1,022

6 1,772 1,866 1,911 1,937 1,962 1,986

(Most Serious) 7 1,866 1,867 1,860 1,855 1,839 1,824

Total 20,031 20,325 20,464 20,504 20,504 20,553

Change from 2015 1.5% 2.2% 2.4% 2.4% 2.6%

Overall Admissions Increasing



AZ Observed and Predicted Yearly

Admission Counts

16,500

17,000

17,500

18,000

18,500

19,000

19,500

20,000

20,500

21,000

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

# o

f A

dm

issi

on

s

Year



AZ Observed and Projected Monthly

Admission Counts

10

01

50

20

02

50

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 1




Admission Counts

12

01

40

16

01

80

20

0

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 2




Admission Counts

15

02

00

25

03

00

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 3




Admission Counts

10

01

50

20

02

50

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 4




Admission Counts

50

60

70

80

90

10

0

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 5




Admission Counts

12

01

40

16

01

80

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 6




Admission Counts

12

01

40

16

01

80

20

02

20

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 7




Admission Counts

30

04

00

50

06

00

70

0

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Category 8




Admission Counts

14

00

15

00

16

00

17

00

18

00

19

00

# o

f A

dm

s

Dec

10

Dec

12

Dec

14

Dec

16

Dec

18

Dec

20

Month

Total




Methodology

Examples

AZ Year-end Stock Projections

Feedback



AZ Year-end Stock Projections –

Flow-based ComponentOffense Seriousness Category 2016 2017 2018 2019 2020

(Least serious) 1 1,027 1,492 1,689 1,761 1,803

2 930 1,232 1,365 1,455 1,518

3 1,918 3,021 3,681 4,137 4,447

4 1,544 2,545 3,159 3,624 3,943

5 769 1,283 1,610 1,858 2,021

6 1,471 2,529 3,237 3,799 4,208

(Most Serious) 7 1,636 3,012 4,218 5,234 6,085

(Drug Offenses) 8 4,891 7,339 8,671 9,664 10,428

Total 14,186 22,452 27,628 31,534 34,455




Flow-based ComponentOffense Seriousness Category 2016 2017 2018 2019 2020

(Least serious) 1 1,027 1,492 1,689 1,761 1,803

2 930 1,232 1,365 1,455 1,518

3 1,918 3,021 3,681 4,137 4,447

4 1,544 2,545 3,159 3,624 3,943

5 769 1,283 1,610 1,858 2,021

6 1,471 2,529 3,237 3,799 4,208

(Most Serious) 7 1,636 3,012 4,218 5,234 6,085

(Drug Offenses) 8 4,891 7,339 8,671 9,664 10,428

Total 14,186 22,452 27,628 31,534 34,455

Contribution to Stock Population Increasing




Stock-based ComponentOffense Seriousness Category 2016 2017 2018 2019 2020

(Least serious) 1 1,184 656 378 210 114

2 983 654 495 387 319

3 2,973 1,860 1,206 763 454

4 3,223 2,246 1,687 1,236 961

5 1,250 784 524 337 228

6 3,108 2,104 1,460 998 691

(Most Serious) 7 10,963 9,651 8,472 7,408 6,489

(Drug Offenses) 8 5,083 2,985 2,050 1,316 812

Total 28,766 20,939 16,272 12,655 10,067




Stock-based ComponentOffense Seriousness Category 2016 2017 2018 2019 2020

(Least serious) 1 1,184 656 378 210 114

2 983 654 495 387 319

3 2,973 1,860 1,206 763 454

4 3,223 2,246 1,687 1,236 961

5 1,250 784 524 337 228

6 3,108 2,104 1,460 998 691

(Most Serious) 7 10,963 9,651 8,472 7,408 6,489

(Drug Offenses) 8 5,083 2,985 2,050 1,316 812

Total 28,766 20,939 16,272 12,655 10,067

Contribution to Stock Population Decreasing





(Least serious) 1 2,259 2,211 2,148 2,067 1,971 1,917

2 2,012 1,913 1,887 1,860 1,842 1,837

3 4,832 4,891 4,880 4,887 4,900 4,900

4 4,768 4,767 4,791 4,846 4,861 4,904

5 1,926 2,019 2,067 2,134 2,195 2,249

6 4,503 4,579 4,632 4,697 4,797 4,899

(Most Serious) 7 12,526 12,599 12,662 12,689 12,642 12,574

(Drug Offenses) 8 9,542 9,973 10,323 10,721 10,980 11,240

Total 42,368 42,952 43,392 43,900 44,189 44,522

Change from 2015 1.4% 2.4% 3.6% 4.3% 5.1%





(Least serious) 1 2,259 2,211 2,148 2,067 1,971 1,917

2 2,012 1,913 1,887 1,860 1,842 1,837

3 4,832 4,891 4,880 4,887 4,900 4,900

4 4,768 4,767 4,791 4,846 4,861 4,904

5 1,926 2,019 2,067 2,134 2,195 2,249

6 4,503 4,579 4,632 4,697 4,797 4,899

(Most Serious) 7 12,526 12,599 12,662 12,689 12,642 12,574

(Drug Offenses) 8 9,542 9,973 10,323 10,721 10,980 11,240

Total 42,368 42,952 43,392 43,900 44,189 44,522

Change from 2015 1.4% 2.4% 3.6% 4.3% 5.1%

Stock Population Decreasing





(Least serious) 1 2,259 2,211 2,148 2,067 1,971 1,917

2 2,012 1,913 1,887 1,860 1,842 1,837

3 4,832 4,891 4,880 4,887 4,900 4,900

4 4,768 4,767 4,791 4,846 4,861 4,904

5 1,926 2,019 2,067 2,134 2,195 2,249

6 4,503 4,579 4,632 4,697 4,797 4,899

(Most Serious) 7 12,526 12,599 12,662 12,689 12,642 12,574

(Drug Offenses) 8 9,542 9,973 10,323 10,721 10,980 11,240

Total 42,368 42,952 43,392 43,900 44,189 44,522

Change from 2015 1.4% 2.4% 3.6% 4.3% 5.1%

Stock Population Increasing





(Least serious) 1 2,259 2,211 2,148 2,067 1,971 1,917

2 2,012 1,913 1,887 1,860 1,842 1,837

3 4,832 4,891 4,880 4,887 4,900 4,900

4 4,768 4,767 4,791 4,846 4,861 4,904

5 1,926 2,019 2,067 2,134 2,195 2,249

6 4,503 4,579 4,632 4,697 4,797 4,899

(Most Serious) 7 12,526 12,599 12,662 12,689 12,642 12,574

(Drug Offenses) 8 9,542 9,973 10,323 10,721 10,980 11,240

Total 42,368 42,952 43,392 43,900 44,189 44,522

Change from 2015 1.4% 2.4% 3.6% 4.3% 5.1%

Overall Stock Population Increasing



37,000

38,000

39,000

40,000

41,000

42,000

43,000

44,000

45,000

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

# in

Ye

ar-e

nd

Sto

ck

Year

AZ Observed and Predicted Year-

end Stocks



Observations from Projections in

Other States

In total, we…

– Predicted population growth for 12 states

– Predicted population decline for 15 states

– Predicted inflection in growth for 12 states




Methodology

Examples

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Additional Feedback?

Would our projections be beneficial for your

state?

Any considerations we missed?

Comments/suggestions?



Contacts

Christopher Cutler, Analyst, Abt AssociatesEmail: [email protected]: 617-520-2441

Tom Rich, Project Director, Abt AssociatesEmail: [email protected]: 617-520-2753

Josh Markman, Program Manager, Bureau of Justice Statistics

Email: [email protected]: 202-616-1718

Thank You!

mailto:[email protected]



projecting state prison populations: an ncrp innovationan ncrp innovation april 5, 2017 authors:...

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