I’ve substantially updated the aoristic macro for SPSS from what I previously posted. The updated code can be found here. The improvements are;

  • Code is much more modularized, it is only 1 function and takes an Interval parameter to determine what interval summaries you want.
  • It includes Agresti-Coull binomial error intervals (95% Confidence Intervals). It also returns a percentage estimate and the total number of cases the estimate is based off of, besides the usual info for time period, split file, and the absolute aoristic estimate.
  • allows an optional command to save the reshaped long dataset

Functionality dropped are default plots, and saving of begin, end and middle times for the same estimates. I just didn’t find these useful (besides academic purposes).

The main motivation was to add in error bars, as I found when I was making many of these charts it was obvious that some of the estimates were highly variable. While the Agresti-Coull binomial proportions are not entirely justified in this novel circumstance, they are better than nothing to at least illustrate the error in the estimates (it seems to me that they will likely be too small if anything, but I’m not sure).

I think a good paper I might work on in the future when I get a chance to is 1) show how variable the estimates are in small samples, and 2) evaluate the asympotic coverages of various estimators (traditional binomial proportions vs. bootstrap I suppose). Below is an example output of the updated macro, again with the same data I used previously. I make the small multiple chart by different crime types to show the variability in the estimates for given sample sizes.

3 comments on"Update for Aoristic Macro in SPSS"

  1. […] cyclical line plots, e.g. aoristic crime estimates by hour of day and day of week. Using the same Arlington data I used before, here are the aoristic estimates for hour of day plotted seperately for each day of the week. The […]

  2. […] to provide a conveniant spreadsheet to calculate aoristic estimates. (I typically do them with my SPSS MACRO – but it won’t be too arduous to expand what I have done here to an excel […]

  3. […] the same burglary data from Arlington I used for my aoristic macro, here is an example plot for a few over 6,300 burglaries in Arlington in 2012 using a fuzz factor […]

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