A previous article describes how to use the SGPANEL procedure to visualize subgroups of data. It focuses on using headers to display information about each graph. In the example, the data are time series for the price of several stocks, and the headers include information about whether the stock price
One of the first things I learned in SAS was how to use PROC PRINT to display parts of a data set. I usually do not need to see all the data, so my favorite way to use PROC PRINT is to use the OBS= data set option to display
Have you ever heard of the DOLIST syntax? You might know the syntax even if you are not familiar with the name. The DOLIST syntax is a way to specify a list of numerical values to an option in a SAS procedure. Applications include: Specify the end points for bins
When there are two equivalent ways to do something, I advocate choosing the one that is simpler and more efficient. Sometimes, I encounter a SAS program that simulates random numbers in a way that is neither simple nor efficient. This article demonstrates two improvements that you can make to your
Finite-precision computations can be tricky. You might know, mathematically, that a certain result must be non-negative or must be within a certain interval. However, when you actually compute that result on a computer that uses finite-precision, you might observe that the value is slightly negative or slightly outside of the
Many textbooks and research papers present formulas that involve recurrence relations. Familiar examples include: The factorial function: Set Fact(0)=1 and define Fact(n) = n*Fact(n-1) for n > 0. The Fibonacci numbers: Set Fib(0)=1 and Fib(1)=1 and define Fib(n) = Fib(n-1) + Fib(n-2) for n > 1. The binomial coefficients (combinations
I got a lot of feedback about my recent article about how to find roots of nonlinear functions by using the SOLVE function in PROC FCMP. A colleague asked how the FCMP procedure stores the functions. Specifically, why the OUTLIB= option on the PROC FCMP statement use a three-level syntax:
Finding the root (or zero) of a nonlinear function is an important computational task. In the case of a one-variable function, you can use the SOLVE function in PROC FCMP to find roots of nonlinear functions in the DATA step. This article shows how to use the SOLVE function to
A common operation in statistical data analysis is to center and scale a numerical variable. This operation is conceptually easy: you subtract the mean of the variable and divide by the variable's standard deviation. Recently, I wanted to perform a slight variation of the usual standardization: Perform a different standardization
I have written several articles about how to work with continuous probability distributions in SAS. I always emphasize that it is important to be able to compute the four essential functions for working with a statistical distribution. Namely, you need to know how to generate random values, how to compute
