CoolData blog

6 October 2014

Don’t worry, just do it

2014-10-03 09.45.37People trying to learn how to do predictive modelling on the job often need only one thing to get them to the next stage: Some reassurance that what they are doing is valid.

Peter Wylie and I are each just back home, having presented at the fall conference of the Illinois chapter of the Association of Professional Researchers for Advancement (APRA-IL), hosted at Loyola University Chicago. (See photos, below!) Following an entertaining and fascinating look at the current and future state of predictive analytics presented by Josh Birkholz of Bentz Whaley Flessner, Peter and I gave a live demo of working with real data in Data Desk, with the assistance of Rush University Medical Center. We also drew names to give away a few copies of our book, Score! Data-Driven Success for Your Advancement Team.

We were impressed by the variety and quality of questions from attendees, in particular those having to do with stumbling blocks and barriers to progress. It was nice to be able to reassure people that when it comes to predictive modelling, some things aren’t worth worrying about.

Messy data, for example. Some databases, particularly those maintained by non higher ed nonprofits, have data integrity issues such as duplicate records. It would be a shame, we said, if data analysis were pushed to the back burner just because of a lack of purity in the data. Yes, work on improving data integrity — but don’t assume that you cannot derive valuable insights right now from your messy data.

And then the practice of predictive modelling itself … Oh, there is so much advice out there on the net, some of it highly technical and involving a hundred different advanced techniques. Anyone trying to learn on their own can get stymied, endlessly questioning whether what they’re doing is okay.

For them, our advice was this: In our field, you create value by ranking constituents according to their likelihood to engage in a behaviour of interest (giving, usually), which guides the spending of scarce resources where they will do the most good. You can accomplish this without the use of complex algorithms or arcane math. In fact, simpler models are often better models.

The workhorse tool for this task is multiple linear regression. A very good stand-in for regression is building a simple score using the techniques outlined in Peter’s book, Data Mining for Fundraisers. Sticking to the basics will work very well. Fussing with technical issues or striving for a high degree of accuracy are distractions that the beginner need not be overly concerned with.

If your shop’s current practice is to pick prospects or other targets by throwing darts, then even the crudest model will be an improvement. In many situations, simply performing better than random will be enough to create value. The bottom line: Just do it. Worry about perfection some other day.

If the decisions are high-stakes, if the model will be relied on to guide the deployment of scarce resources, then insert another step in the process. Go ahead and build the model, but don’t use it. Allow enough time of “business as usual” to elapse. Then, gather fresh examples of people who converted to donors, agreed to a bequest, or made a large gift — whatever the behaviour is you’ve tried to predict — and check their scores:

  • If the chart shows these new stars clustered toward the high end of scores, wonderful. You can go ahead and start using the model.
  • If the result is mixed and sort of random-looking, then examine where it failed. Reexamine each predictor you used in the model. Is the historical data in the predictor correlated with the new behaviour? If it isn’t, then the correlation you observed while building the model may have been spurious and led you astray, and should be excluded. As well, think hard about whether the outcome variable in your model is properly defined: That is, are you targeting for the right behaviour? If you are trying to find good prospects for Planned Giving, for example, your outcome variable should focus on that, and not lifetime giving.

“Don’t worry, just do it” sounds like motivational advice, but it’s more than that. The fact is, there is only so much model validation you can do at the time you create the model. Sure, you can hold out a generous number of cases as a validation sample to test your scores with. But experience will show you that your scores will always pass the validation test just fine — and yet the model may still be worthless.

A holdout sample of data that is contemporaneous with that used to train the model is not the same as real results in the future. A better way to go might be to just use all your data to train the model (no holdout sample), which will result in a better model anyway, especially if you’re trying to predict something relatively uncommon like Planned Giving potential. Then, sit tight and observe how it does in production, or how it would have done in production if it had been deployed.

  1. Observe, learn, tweak, and repeat. Errors are hard to avoid, but they can be discovered.
  2. Trust the process, but verify the results. What you’re doing is probably fine. If it isn’t, you’ll get a chance to find out.
  3. Don’t sweat the small stuff. Make a difference now by sticking to basics and thinking of the big picture. You can continue to delve and explore technical refinements and new methods, if that’s where your interest and aptitude take you. Data analysis and predictive modelling are huge subjects — start where you are, where you can make a difference.

* A heartfelt thank you to APRA-IL and all who made our visit such a pleasure, especially Sabine Schuller (The Rotary Foundation), Katie Ingrao and Viviana Ramirez (Rush University Medical Center), Leigh Peterson Visaya (Loyola University Chicago), Beth Witherspoon (Elmhurst College), and Rodney P. Young, Jr. (DePaul University), who took the photos you see below. (See also: APRA IL Fall Conference Datapalooza.)

Click on any of these for a full-size image.

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