Articles and News

What are the odds of developing a brain tumor from long-term use of cell phones? This is an evolving area of research.  Some studies have found an association and others have not. But two recent meta-analyses suggest that the odds are about 33 to 44% greater due to long-term cell phone usage. Got your attention?…

What are the lifetime odds of dying from being hit by a meteorite? 1 in 1,600,000. Yep, not very likely.  You are much more likely to die from a dog attack (1 in 86,781) or from a lightning strike (1 in 138,849). But why odds? Why not express these likelihoods in terms of probabilities?  Seems…

First time users of Tableau often get tripped up over the default Tableau SUM aggregation.  Here is what I mean. Suppose the question is to find the average of SALES PER VISIT (sales measured across the preceding 6 months) among the males and females in a sample of 25 shoppers.  The data look like this…

“Big data.” We checked in with Google search trends recently. Appears that “Big Data” has lost its luster search-wise…started trending down about 4 years ago. Nowadays, everything is big data? Implications of big data However, this does not mean we should lose sight of certain statistical implications associated with being “big”. Yes, large amounts of…

We just noticed that it has been a full year since we started posting daily updates to our San Diego County COVID-19 dashboard. This dashboard tracks the San Diego COVID experience: new cases, tests, and positivity rates at the county-level as well as new cases for each of the county’s ZIP Codes. On this first-year…

You like potato and I like potahto You like tomato and I like tomahto Potato, potahto, tomato, tomahto Let’s call the whole thing off But oh, if we call the whole thing off Then we must part And oh, if we ever part then that might break my heart —Ira Gershwin The eye-popping efficacy rates…

In case you missed it, we are in a recession. According to Intensity’s latest US recession start date forecast, there is a 50% probability of a recession starting sometime in the January to February 2019 period.  And a 97% probability of it starting sometime within the next 6 months. Their “point estimate” of a recession…

“A good forecaster is not smarter than everyone else, he merely has his ignorance better organized.” ― Anonymous Predicting the future is an exercise in probability rather than certainty. As we have mentioned several times over the course of these articles, your forecast model will be wrong. It is just a matter of how useful…

“There are two kinds of forecasters: those who don’t know, and those who don’t know they don’t know.” ― John Kenneth Galbraith After an extensive model building and vetting process, along the lines we previously discussed here and here, the practical forecaster may still be left with several strong performing models. These models perform similarly…

“Prediction is very difficult, especially if it’s about the future.” ― Niels Bohr, physicist Holdout samples are a key component to estimating a “useful” forecasting model. Set aside data at least equal in length to your forecast horizon (“holdout sample”). Build your models on the remaining data (“modeling sample”). And compare the candidate models’ forecast…