The DO Loop
Statistical programming in SAS with an emphasis on SAS/IML programs
Nearly every statistician has heard the aphorism, "All models are wrong, but some are useful." The quote is attributed to George Box, an early and influential thinker about statistics. Did George Box actually say this quote? Yes, he did. The first part of the quote ("All models are wrong") appeared
After giving a talk about how to create effective statistical graphics in SAS, I was asked a question: "When do you suggest using the graph template language (GTL) to build graphs?" I replied that I turn to the GTL when I cannot create the graph I want by using PROC
A common task in statistics is to model data by using a parametric probability distribution, such as the normal, lognormal, beta, or gamma distributions. There are many ways to assess how well the model fits the data, including graphical methods such as a Q-Q plot and formal statistical tests such
Every programmer makes errors. Therefore, learning to debug a program is an important part of learning to program. Another skill is learning to decipher cryptic error messages, which can be as hard to interpret as hieroglyphs. One helpful skill is learning to navigate a "traceback" error. A traceback error message
Happy Pi Day! Every year on March 14th (written 3/14 in the US), people in the mathematical sciences celebrate "all things pi-related" because 3.14 is the three-decimal approximation to π ≈ 3.14159265358979.... The purpose of this day is to have fun, celebrate the importance of mathematics, and maybe learn a
The first-order autoregressive (AR(1)) correlation structure is important for applications in time series modeling and for repeated measures analysis. The AR(1) model provides a simple situations where measurements (on the same subject) that are closer in time are correlated more strongly than measurements recorded far apart. The AR(1) model uses