Rick Wicklin, PhD, is a distinguished researcher in computational statistics at SAS and is a principal developer of SAS/IML software. His areas of expertise include computational statistics, simulation, statistical graphics, and modern methods in statistical data analysis. Rick is author of the books Statistical Programming with SAS/IML Software and Simulating Data with SAS.
It is easy to use the SGPLOT procedure in SAS to plot the graph of a well-behaved continuous function: just create a data set of the (x,y) values on some domain and use the SERIES statement to connect the points. However, to plot the graph of a discontinuous function correctly
Someone recently asked a question on the SAS Support Communities about estimating parameters in ridge regression. I answered the question by pointing to a matrix formula in the SAS documentation. One of the advantages of the SAS/IML language is that you can implement matrix formulas in a natural way. The
One purpose of this International Year of Statistics is to spread the word that the field of statistics benefits society. As part of the International Year, many organizations, including SAS and the American Statistical Association (ASA), are turning to history to illustrate how statistics is vital to the health and
Argh! I've just spilled coffee on output that shows the least squares coefficients for a regression model that I was investigating. Now the parameter estimate for the intercept is completely obscured, although I can still see the parameter estimates for the coefficients of the continuous explanatory variable. What can I
Last week there was an interesting question posted to the "Stat-Math Statistics" group on LinkedIn. The original question was a little confusing, so I'll state it in a more general form: A population is normally distributed with a known mean and standard deviation. A sample of size N is drawn
There is something for everyone at SAS Global Forum 2013. I like to attend presentations in the Statistics and Data Analysis track and talk with SAS customers in the SAS Support and Demo Area. But one activity that I enjoy the most is to stroll through the poster area and
I am pleased to announce that the documentation for the IMLPlus language is now available online. Previously, this resource was available only from within the SAS/IML Studio application. This documentation can now be accessed by anyone, regardless of whether they have installed SAS/IML Studio. As I have described previously, IMLPlus
A SAS user asked an interesting question on the SAS/GRAPH and ODS Graphics Support Forum. The question is: Does PROC SGPLOT support a way to display the slope of the regression line that is computed by the REG statement? Recall that the REG statement in PROC SGPLOT fits and displays
The SAS/IML language has a curious syntax that enables you to specify a "repetition factor" when you initialize a vector of literal values. Essentially, the language enables you to specify the frequency of an element. For example, suppose you want to define the following vector: proc iml; x = {1
I have previously written about how to use the "table" distribution to generate random values from a discrete probability distribution. For example, if there are 50 black marbles, 20 red marbles, and 30 white marbles in a box, the following SAS/IML program simulates random draws (with replacement) of 1,000 marbles:
