 |
For Fentress Inc., Crystal Ball Pro is
the Key to Forecasting Prison Populations
CUSTOMER OF THE MONTH (APRIL, 1999)
|
Fentress Incorporated, a Baltimore-Washington based consulting
firm, specializes in resource planning for various U.S. criminal
justice organizations. Tom Rubino, an Economist/Statistician at
Fentress, is responsible for designing studies that address such
long-range issues as personnel requirements and workload planning
for these organizations. In the mid-1990s, when the Prisoner Services
Division of the US Marshals Service (USMS) had limited success in
predicting prisoner populations, they turned to Fentress, Rubino,
and Crystal Ball Pro for a solution.
Forecasting the complex flow of prisoners through the criminal
justice system is difficult due to the variety of potential paths
and the length of time involved along each particular path. For
example, one prisoner might quickly plea bargain and go to prison
while another might plead innocent and go to a lengthy trial. In
addition, the USMS is made up of 94 districts, each with distinct
pathways and prison populations. Until very recently, only limited
prisoner data was available to the USMS, which meant that only certain
statistical methods, such as Regression Methods, Moving Average
Methods, and Simple Trending Models, could be applied for forecasting.
The results of these methods posed a serious problem for the USMS
because it ran the risk of operating under a budget shortfall if
the forecasts were lower than the actual number of incarcerated
prisoners. Given this situation, it was decided - through a collaborative
effort that included Fentress Incorporated, the Bureau of Prisons
and the USMS - that simulation modeling was the best method for
understanding dynamic prisoner populations.
The Prisoners Services Division approached Fentress for a simulation-based
solution, which Fentress demonstrated through a combination of spreadsheet
models and Crystal Ball distributions. These models forecast the
monthly prisoner population by federal judicial district. Next,
each district's monthly forecasts were averaged to create an average
annual prisoner population statistic. The Prisoners Services Division
hired Fentress and adopted the models, which finally allow USMS
managers to realistically plan their budgetary needs. "More importantly,"
Rubino added, "we are giving our clients credibility in requesting
resources. The bottom line is to provide efficient criminal justice,
and that can't be done with inefficient budgeting."
Rubino regularly employs the Bootstrap Extender to build confidence
intervals around prisoner population forecasts, and these intervals
define the probability of underfunding the program. Rubino also
regards Crystal Ball's automated Report function and the Developer
Kit as essential to his work. Crystal Ball reports help Fentress
and client managers explain the simulation results to a general
audience and to increase the efficiency with which Fentress builds
each of the 94 district models. The Developer Kit has been used
to automate the simulation process and report creation for each
district model.
Two other organizations that Fentress consults for are the Executive
Office for US Attorneys and the Administrative Office of the US
Courts. For the US Attorneys, Fentress's models predict personnel
requirements, specifically how many Full Time Equivalent (FTE) positions
are required to cover work generated in future fiscal years. Long-range
facility planning studies for the US Courts identify the need for
new federal courthouses around the country, and they plan for the
courthouse usage over the next thirty years.
As for the future, Rubino expects that CB Pro will be a regular
tool for forecasting projects. Fentress anticipates applying optimization
to their prisoner population models, and they will probably move
to CB Turbo to reduce the time required for scenario testing. "CB
Pro opened the doors for a number of new contracts and has given
us credibility throughout the Department of Justice," said Rubino.
|
