qldyjcost

Cost of Offending Tools for Youth Justice in Queensland

Purpose

This is a simple, lightweight R package purely for convenience for my day job as a Lead Data Scientist at the consulting firm Nous Group where I frequently conduct evaluations for Queensland Youth Justice.

Installation

You can install the development version of qldyjcost from GitHub using the following:

devtools::install_github("hendersontrent/qldyjcost")

Usage

The core of qldyjcost is a data frame of historical costs from peer-reviewed sources called yjcosts. It can be accessed easily via:

library(qldyjcost)
head(yjcosts)

  qasoc_code                   qasoc_description  type  cost      fy
1          1       Homicide and related offences Court 19674 2016-17
2          2       Acts intended to cause injury Court  1165 2016-17
3          3 Sexual assault and related offences Court  6543 2016-17
4          4         Dangerous or negligent acts Court   508 2016-17
5          5     Abduction, harassment and other Court  2076 2016-17
6          6      Robbery, extortion and related Court  3021 2016-17

yjcosts contains historical offending costs broken down by offence seriousness for court costs, police costs, wider social costs, and custody costs.

qldyjcost also contains functionality for adjusting the historical offending costs to values for a given financial year using inflation. The get_cpi function webscrapes inflation rates from the Australian Bureau of Statistics and automatically cleans it up ready for use:

cpi <- get_cpi(location = "Australia")
head(cpi)

        year inflation_index      fy
1 1948-09-03             3.7 1948-49
2 1948-12-03             3.8 1948-49
3 1949-03-03             3.9 1948-49
4 1949-06-03             4.0 1948-49
5 1949-09-03             4.1 1949-50
6 1949-12-03             4.1 1949-50

Instead of grabbing CPI for the country, we can instead get it for any capital city:

cpi_bris <- get_cpi(location = "Brisbane")
head(cpi_bris)

        year inflation_index      fy
1 1948-09-03             3.7 1948-49
2 1948-12-03             3.7 1948-49
3 1949-03-03             3.8 1948-49
4 1949-06-03             3.9 1948-49
5 1949-09-03             4.0 1949-50
6 1949-12-03             4.1 1949-50

While this function is useful in isolation, it forms a key component of the workhorse function of yjcosts which is adjust_costs. adjust_costs applies inflation adjustments to the offending cost data to any given financial year. Specifically, it does this by averaging CPI values for each FY associated with the baseline costs in yjcosts as well as the user-specified FY to adjust to. The interface is incredible simple. Here is how to adjust costs to FY 2023-24 dollars:

adj <- adjust_costs(fy = "2023-24", location = "Australia")
head(adj)

# A tibble: 6 × 9
  qasoc_code qasoc_description                   type   cost fy      new_fy  avg_cpi_old avg_cpi_new new_cost
       <dbl> <chr>                               <chr> <dbl> <chr>   <chr>         <dbl>       <dbl>    <dbl>
1          1 Homicide and related offences       Court 19674 2016-17 2023-24        110.        136.   44012.
2          2 Acts intended to cause injury       Court  1165 2016-17 2023-24        110.        136.    2605.
3          3 Sexual assault and related offences Court  6543 2016-17 2023-24        110.        136.   14636.
4          4 Dangerous or negligent acts         Court   508 2016-17 2023-24        110.        136.    1135.
5          5 Abduction, harassment and other     Court  2076 2016-17 2023-24        110.        136.    4643.
6          6 Robbery, extortion and related      Court  3021 2016-17 2023-24        110.        136.    6757.