Weighted Displacement Difference Calculator

This is a demonstration of how CRIME De-Coder can provide your agency with simple tools to conduct rigorous crime analysis.

This tool calculates the Weighted Displacement Difference, an estimate of the total number of crimes reduced given an input treated area vs control areas. See Wheeler and Ratcliffe (2018) for an empirical reference on the method and for advice on applying the method.

For brief instructions, calculate crime counts in your treated and control areas pre and post your intervention. (If you do not have displacement areas, you can insert 0's into those input fields.) Hit the Calculate button, and you will be presented with estimates of the total crime reduction, along with estimates of the standard error and a confidence interval for that crime reduction.

Notes: This is run entirely client side using javascript, I do not store any of the values you input into these forms. The tool does not conduct any data validation. Inputs only make sense for positive crime counts. Do not input negative numbers or non-integer values. For additional WDD metrics for different time periods or weighted by area or population, see my ptools R package.