Download presentation

Presentation is loading. Please wait.

Published byThomas Hewitson Modified over 3 years ago

1
Forecasting using Discrete Event Simulation for the NZ Prison Population Dr Jason (Qingsheng) Wang Mr Ross Edney Ministry of Justice

2
2 Prison Population Projections The prison population in NZ has grown steadily over the last decade The prisoner population is the end result of a chain of complex causal factors Serious crime, apprehensions, investigations, prosecutions and court cases which can involve variable periods of remand are precursors to imprisonment The opportunity cost of excess prison beds is high The costs of bed shortages is also high due in part to risks to staff and prisoner safety Several years of planning is required to build a prison so accurate forecasts are important

3
3 Discrete Event Simulation (DES) DES treats each prisoner entering the prison system separately and assigns the time that will be spent in prison so there is an entry date and exit date The technique “releases” prisoners from the virtual prison system when they have served their sentence DES can support multiple inflows A forecast track for the prisoner population can be derived by using the inflow and stay-time data

4
4 Remand Prison Population DES Model and Its Direct Drivers Remand prisoner inflows/arrivals Time spend on remand

5
5 Sentenced Prison Population DES Model and Its Direct Drivers Sentenced prisoner inflows/arrivals Given sentence for each arrived prisoners Proportion of sentence served

6
6 Determining Forecast Assumptions Historic data is employed to derive key input assumptions Time series and expert opinion is used to form a view of the likely direction of key driver variables Experts provide independent input on the impact of new policy that may affect, for example, custodial sentences and their length during the forecast horizon

7
7 2006 Forecast, Sentenced Inflow

8
8 2006 Forecast, Proportion Served

9
9 2006 Forecast, Male Sentenced

10
10 2006 Forecast, Male Remand

11
11 2006 Forecast Performance, Including EI after New Sentences

12
12 DES Monte-Carlo Model, Confidence Intervals, and Capacity Planning Buffer Instead of using fixed mean values, the distributional DES model will feed the direct drivers with distributional values. Monte Carlo simulation will generate the population/muster probability distribution so to identify peak demand and risks over the planning horizon Policy simulation: this approach can be applied in policy changes with distributional impact

13
13 Sentenced Distributional DES Model

14
14 Remand Monthly Inflow and Distribution Using normal distribution of Holt-Winters model residuals and prediction errors

15
15 Time on Remand Distributions Annual empirical distributions

16
16 Remand Muster Monte-Carlo, Male

17
17 Muster Distribution Normality Test Cross-Section Distributions, Remand

18
18 Standardised Monte-Carlo, Remand

19
19 Standardised Monte-Carlo’s Distributions, Remand

20
20 Standardised Monte-Carlo Distribution, Sentenced

21
21 Forecast Confidence Intervals with Normal Distribution and Empirical Distribution

22
22 Volatility Buffer Calculation Assuming Normal Distributions

23
23 End Thank you

24
24 Jarque-Bera Test, Remand

25
25 Sentenced Distributional DES Model Inflows and Distributions

26
26 Sentenced Distributional DES Model Given Sentence Distributions

27
27 Sentenced Distributional DES Model Proportion Served Distributions

28
28 Proportion Served Distributions

29
29 Sentenced Muster Monte-Carlo, Male

30
30 Jarque-Bera Test, Sentenced Male

Similar presentations

OK

Jeopardy Q 1 Q 6 Q 11 Q 16 Q 21 Q 2 Q 7 Q 12 Q 17 Q 22 Q 3 Q 8 Q 13

Jeopardy Q 1 Q 6 Q 11 Q 16 Q 21 Q 2 Q 7 Q 12 Q 17 Q 22 Q 3 Q 8 Q 13

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Download ppt on fundamental rights and duties of india Ppt on three layers of the earth Ppt on pin diode attenuator A ppt on albert einstein Ppt on home automation using gsm Free download ppt online shopping project Ppt on social media in india Ppt on acid rain Ppt on regional transport office india Water safety for kids ppt on batteries