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.

DSC_0017 DSC_0018 DSC_0026 DSC_0051 DSC_0054 DSC_0060 DSC_0066 DSC_0075 DSC_0076 DSC_0091

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16 July 2013

Alumni engagement scoring vs. predictive modelling

Filed under: Alumni, engagement, predictive modeling — Tags: , , , — kevinmacdonell @ 8:06 am

Alumni engagement scoring has an undeniable appeal. What could be simpler? Just add up how many events an alum has attended, add more points for volunteering, add more points for supporting the Annual Fund, and maybe some points for other factors that seem related to engagement, and there you have your score. If you want to get more sophisticated, you can try weighting each score input, but generally engagement scoring doesn’t involve any advanced statistics and is easily grasped.

Not so with predictive modelling, which does involve advanced stats and isn’t nearly as intuitive; often it’s not possible to really say how an input variable is related to the outcome. It’s tempting, too, to think of an engagement score as being a predictor of giving and therefore a good replacement for modelling. Actually, it should be predictive — if it isn’t, your score is not measuring the right things — but an engagement score is not the same thing as a predictive model score. They are different tools for different jobs.

Not only are engagement scoring schemes different from predictive models, their simplicity is deceptive. Engagement scoring is incomplete without some plan for acting on observed trends with targeted programming. This implies the ability to establish causal drivers of engagement, which is a tricky thing.

That’s a sequence of events — not a one-time thing. In fact, engagement scoring is like checking the temperature at regular intervals over a long period of time, looking for up and down trends not just for the group as a whole but via comparisons of important subgroups defined by age, sex, class year, college, degree program, geography or other divisions. This requires discipline: taking measurements in exactly the same way every year (or quarter, or what-have-you). If the score is fed by a survey component, you must survey constantly and consistently.

Predictive models and engagement scores have some surface similarities. They share variables in common, the output of both is a numerical score applied to every individual, and both require database work and math in order to calculate them. Beyond that, however, they are built in different ways and for different purposes. To summarize:

  • Predictive models are collections of potentially dozens of database variables weighted according to strength of correlation with a well-defined behaviour one is trying to predict (eg. making a gift), in order to rank individuals by likelihood to engage in that behaviour. Both Alumni Relations and Development can benefit from the use of predictive models.
  • Engagement scores are collections of a very few selectively-chosen database variables, either not weighted or weighted according to common sense and intuition, in order to roughly quantify the quality of “engagement”, however one wishes to define that term, for each individual. The purpose is to allow comparison of groups (faculties, age bands, geographical regions, etc.) with each other. Comparisons may be made at one point in time, but it is more useful to compare relative changes over time. The main user of scores is Alumni Relations, in order to identify segments requiring targeted programming, for example, and to assess the impact of programming on targeted segments over time.

Let’s explore key differences in more depth:

The purpose of modelling is prediction, for ranking or segmentation. The purpose of engagement scoring is comparison.

Predictive modelling scores are not usually included in reports. Used immediately in decision making, they may never be seen by more than one or two people. Engagement scores are included in reports and dashboards, and influence decision-making over a long span of time.

The target variable of a predictive model is quantifiable (eg. giving, measurable in dollars). In engagement scoring, there is no target variable, only an output – a construct called “engagement”, which itself is not directly measurable.

Potential input variables for predictive models are numerous (100+) and vary from model to model. Input variables for engagement scores are limited to a handful of easily measured attributes (giving, event attendance, volunteering) which must remain consistent over time.

Variables for predictive models are chosen primarily using statistical methods (correlation) and only secondarily using judgment and “common sense.” For example, if the presence of a business phone number is highly correlated with being a donor, it may be included in the model. For engagement scores, variables are chosen by consensus of stakeholders, primarily according to subjective standards. For example, event attendance and giving would probably be deemed by the committee to indicate engagement, and would therefore be included in the score. Advanced statistics rarely come into play. (For more thoughts on this, read How you measure alumni engagement is up to you.)

In predictive models, giving and variables related to the activity of giving are usually excluded as variables (if ‘giving’ is what we are trying to predict). Using any aspect of the target variable as an input is bad practice in predictive modelling and is carefully avoided. You wouldn’t, for example, use attendance at a donor recognition event to predict likelihood to give. In engagement scoring, though, giving history is usually a key input, as it is common sense to believe that being a donor is an indication of engagement. (It might be excluded or reported separately if the aim is to demonstrate the causal link between engagement indicators and giving.)

Modelling variables are weighted using multiple linear regression or other statistical method which calculates the relative influence of each variable while simultaneously controlling for the influence of all other variables in the model. Engagement score variables are usually weighted according to gut feel. For example, coming to campus for Homecoming seems to carry more weight than showing up for a pub night in one’s own city, therefore we give it more weight.

The quality of a predictive model is testable, first against a validation data set, and later against actual results. But there is no right or wrong way to estimate engagement, therefore the quality of scores cannot be evaluated conclusively.

The variables in a predictive model have complex relationships with each other that are difficult or impossible to explain except very generally. Usually there is no reason to explain a model in detail. The components in an engagement score, on the other hand, have plausible (although not verifiable) connections to engagement. For example, volunteering is indicative of engagement, while Name Prefix is irrelevant.

Predictive models are built for a single, time-limited purpose and then thrown away. They evolve iteratively and are ever-changing. On the other hand, once established, the method for calculating an engagement score must not change if comparisons are to be made over time. Consistency is key.

Which is all to say: alumni engagement scoring is not predictive modelling. (And neither is RFM analysis.) Only predictive modelling is predictive modelling.

20 September 2012

When less data is more, in predictive modelling

When I started doing predictive modelling, I was keenly interested in picking the best and coolest predictor variables. As my understanding deepened, I turned my attention to how to define the dependent variable in order to really get at what I was trying to predict. More recently, however, I’ve been thinking about refining or limiting the population of constituents to be scored, and how that can help the model.

What difference does it make who gets a propensity score? Up until maybe a year ago, I wasn’t too concerned. Sure, probably no 22-year-old graduate had ever entered a planned giving agreement, but I didn’t see any harm in applying a score to all our alumni, even our youngest.

Lately, I’m not so sure. Using the example of a planned gift propensity model, the problem is this: Young alumni don’t just get a score; they also influence how the model is trained. If all your current expectancies were at least 50 before they decided to make a bequest, and half your alumni are under 30 years old, then one of the major distinctions your model will make is based on age. ANY alum over 50 is going to score well, regardless of whether he or she has any affinity to the institution, simply because 100% of your target is in that age group.

The model is doing the right thing by giving higher scores to older alumni. If ages in the sample range from 21 to 100+, then age as a variable will undoubtedly contribute to a large chunk of the model’s ability to “explain” the target. But this hardly tells us anything we didn’t already know. We KNOW that alumni don’t make bequest arrangements at age 22, so why include them in the model?

It’s not just the fact that their having a score is irrelevant. I’m concerned about allowing good predictor variables to interact with ‘Age’ in a way that compromises their effectiveness. Variables are being moderated by ‘Age’, without the benefit of improving the model in a way that we get what we want out of it.

Note that we don’t have to explicitly enter ‘Age’ as a variable in the model for young alumni to influence the outcome in undesirable ways. Here’s an example, using event attendance as a predictor:

Let’s say a lot of very young alumni and some very elderly constituents attend their class reunions. The older alumni who attend reunions are probably more likely than their non-attending classmates to enter into planned giving agreements — for my institution, that is definitely the case. On the other hand, the young alumni who attend reunions are probably no more or less likely than their non-attending peers to consider planned giving — no one that age is a serious prospect. What happens to ‘event attendance’ as a predictor in which the dependent variable is ‘Current planned giving expectancy’? … Because a lot of young alumni who are not members of the target variable attended events, the attribute of being an event attendee will be associated with NOT being a planned giving expectancy. Or at the very least, it will considerably dilute the positive association between predictor and target found among older alumni.

I confirmed this recently using some partly made-up data. The data file started out as real alumni data and included age, a flag for who is a current expectancy, and a flag for ‘event attendee’. I massaged it a bit by artificially bumping up the number of alumni under the age of 50 who were coded as having attended an event, to create a scenario in which an institution’s events are equally popular with young and old alike. In a simple regression model with the entire alumni file included in the sample, ‘event attendance’ was weakly associated with being a planned giving expectancy. When I limited the sample to alumni 50 years of age and older, however, the R squared statistic doubled. (That is, event attendance was about twice as effective at explaining the target.) Conversely, when I limited the sample to under-50s, R squared was nearly zero.

True, I had to tamper with the data in order to get this result. But even had I not, there would still have been many under-50 event attendees, and their presence in the file would still have reduced the observed correlation between event attendance and planned giving propensity, to no useful end.

You probably already know that it’s best not to lump deceased constituents in with living ones, or non-alumni along with alumni, or corporations and foundations along with persons. They are completely distinct entities. But depending on what you’re trying to predict, your population can fruitfully be split along other, more subtle distinctions. Here are a few:

  • For donor acquisition models, in which the target value is “newly-acquired donor”, exclude all renewed donors. You strictly want to have only newly-acquired donors and never-donors in your model. Your good prospects for conversion are the never-donors who most resemble the newly-acquired donors. Renewed donors don’t serve any purpose in such a model and will muddy the waters considerably.
  • Conversely, remove never-donors from models that predict major giving and leadership-level annual giving. Those higher-level donors tend not to emerge out of thin air: They have giving histories.
  • Looking at ‘Age’ again … making distinctions based on age applies to major-gift propensity models just as it does to planned giving propensity: Very young people do not make large gifts. Look at your data to find out at what age donors were when they first gave $1,000, say. This will help inform what your cutoff should be.
  • When building models specifically for Phonathon, whether donor-acquisition or contact likelihood, remove constituents who are coded Do Not Call or who do not have a valid phone number in the database, or who are unlikely to be called (international alumni, perhaps).
  • Exclude international alumni from event attendance or volunteering likelihood models, if you never offer involvement opportunities outside your own country or continent.

Those are just examples. As for general principles, I think both of the following conditions must be met in order for you to gain from excluding a group of constituents from your model. By a “group” I mean any collection of individuals who share a certain trait. Choose to exclude IF:

  1. Nearly 100% of constituents with the trait fall outside the target behaviour (that is, the behaviour you are trying to predict); AND,
  2. Having a score for people with that trait is irrelevant (that is, their scores will not result in any action being taken with them, even if a score is very low or very high).

You would apply the “rules” like this … You’re building a model to predict who is most likely to answer the phone, for use by Phonathon, and you’re wondering what to do with a bunch of alumni who are coded Do Not Call. Well, it stands to reason that 1) people with this trait will have little or no phone contact history in the database (the target behaviour), and 2) people with this trait won’t be called, even if they have a very high contact-likelihood score. The verdict is “exclude.”

It’s not often you’ll hear me say that less (data) is more. Fewer cases in your data file will in fact tend to depress your model’s R squared. But your ultimate goal is not to maximize R squared — it’s to produce a model that does what you want. Fitting the data is a good thing, but only when you have the right data.

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