Simplicity is the king

"If you can't explain it simply, you don't understand it well enough." -- Albert Einstein

Today I had a conversation about a very interesting churn model that we may try to build. The model will let us assess impact of different factors on churn, one of those factors is price, or to be precise, pricing changes. When the conversation ventured to the problem at hand, which is to quantify the impact of the most recent price change, I had to explain that I do not want to put this price change into the model. This is anathema to someone with an interest in econometrics, however, there is not as much driven by the scientific truth as by communication, i.e. being able to explain your results. Though adding the most recent data will improve the model, it is unlikely to help with understanding of the issue at hand by those with little knowledge of regression.Having a known coefficient is good, but it is hard to explain what this coefficient means to layperson. Even if you express it in the form of elasticity, let's say, your churn goes up by 1.5% per every percent of a price increase, it does not quite mean anything to most executives. The alternative approach we agreed upon was to build the model on the data before the price increase, and then determine the churn baseline for every segment we are tracking. Then, we can compare post price change churn to that baseline to show the difference. For example, you had a 2% rate increase for this group of customers, and their churn was 6% compared to 3% we would have expected with no price increase. That is something people can understand.

Another example of simplification to aid communication is the correlation analysis I have done a few years ago. For every variable X correlated to my output Y (sales), I would create a bar chart of Y by grouping subjects with "low X", "medium X" and "high X". This spoke better than any scatterplots or correlation numbers. The only difference is correlation in time between two variables - when shown on a nice chart and visibly correlated they make the best case for making executives feel smart.