The DO Loop
Statistical programming in SAS with an emphasis on SAS/IML programs
Many people know that you can use "WHERE processing" in SAS to filter observations. A typical use is to process only observations that match some criterion. For example, the following WHERE statement processes only observations for male patients who have high blood pressure: WHERE Sex='Male' & Systolic > 140; In
A previous article shows how to compute the probability density function (PDF) for the multivariate normal distribution. In a similar way, you can compute the density function for the multivariate t distribution. This article discusses the density function for the multivariate t distribution, shows how to compute it, and visualizes
Recently, I needed to solve an optimization problem in which the objective function included a term that involved the quantile function (inverse CDF) of the t distribution, which is shown to the right for DF=5 degrees of freedom. I casually remarked to my colleague that the optimizer would have to
For a linear regression model, a useful but underutilized diagnostic tool is the partial regression leverage plot. Also called the partial regression plot, this plot visualizes the parameter estimates table for the regression. For each effect in the model, you can visualize the following statistics: The estimate for each regression
The ODS GRAPHICS statement in SAS supports more than 30 options that enable you to configure the attributes of graphs that you create in SAS. Did you know that you can display the current set of graphical options? Furthermore, did you know that you can temporarily set certain options and
A palindrome is a sequence of letters that is the same when read forward and backward. In brief, if you reverse the sequence of letters, the word is unchanged. For example, 'mom' and 'racecar' are palindromes. You can extend the definition to phrases by removing all spaces and punctuation marks