The DO Loop

Programming Tips

Strengthen your programming skills with tips and techniques from the experts

Analytics | Learn SAS | Programming Tips

Process flow diagram shows how to resample data to create a bootstrap distribution.

Rick WicklinDecember 12, 2018 8

The essential guide to bootstrapping in SAS

This article describes best practices and techniques that every data analyst should know before bootstrapping in SAS. The bootstrap method is a powerful statistical technique, but it can be a challenge to implement it efficiently. An inefficient bootstrap program can take hours to run, whereas a well-written program can give

English

Learn SAS | Programming Tips

Rick WicklinDecember 5, 2018 1

When is a histogram not a histogram? When it's a table!

Recently a SAS programmer wanted to obtain a table of counts that was based on a histogram. I showed him how you can use the OUTHIST= option on the HISTOGRAM statement in PROC UNIVARIATE to obtain that information. For example, the following call to PROC UNIVARIATE creates a histogram for

English

Programming Tips

Rick WicklinNovember 28, 2018 11

Singular parameterizations, generalized inverses, and regression estimates

I remember the first time I used PROC GLM in SAS to include a classification effect in a regression model. I thought I had done something wrong because the parameter estimates table was followed by a scary-looking note: Note: The X'X matrix has been found to be singular, and a

English

Learn SAS | Programming Tips

Rick WicklinNovember 19, 2018 2

Select ODS tables by using wildcards and regular expressions in SAS

You might know that you can use the ODS SELECT statement to display only some of the tables and graphs that are created by a SAS procedure. But did you know that you can use a WHERE clause on the ODS SELECT statement to display tables that match a pattern?

English

Analytics | Data Visualization | Programming Tips

Rick WicklinNovember 14, 2018 13

Create and compare ROC curves for any predictive model

An ROC curve graphically summarizes the tradeoff between true positives and true negatives for a rule or model that predicts a binary response variable. An ROC curve is a parametric curve that is constructed by varying the cutpoint value at which estimated probabilities are considered to predict the binary event.

English

Programming Tips

Rick WicklinNovember 7, 2018 1

Visualize the feasible region for a constrained optimization

When solving optimization problems, it is harder to specify a constrained optimization than an unconstrained one. A constrained optimization requires that you specify multiple constraints. One little typo or a missing minus sign can result in an infeasible problem or a solution that is unrelated to the true problem. This

English

Data Visualization | Learn SAS | Programming Tips

Rick WicklinOctober 31, 2018 5

A trick to plot groups in PROC SGPLOT

A useful feature in PROC SGPLOT is the ability to easily visualize subgroups of data. Most statements in the SGPLOT procedure support a GROUP= option that enables you to overlay plots of subgroups. When you use the GROUP= option, observations are assigned attributes (colors, line patterns, symbols, ...) that indicate

English

Programming Tips

Rick WicklinOctober 29, 2018 1

Bootstrap regression estimates: Residual resampling

If you want to bootstrap the parameters in a statistical regression model, you have two primary choices. The first, case resampling, is discussed in a previous article. This article describes the second choice, which is resampling residuals (also called model-based resampling). This article shows how to implement residual resampling in

English

Analytics | Learn SAS | Programming Tips

Rick WicklinOctober 24, 2018 1

Bootstrap regression estimates: Case resampling

If you want to bootstrap the parameters in a statistical regression model, you have two primary choices. The first is case resampling, which is also called resampling observations or resampling pairs. In case resampling, you create the bootstrap sample by randomly selecting observations (with replacement) from the original data. The

English

Programming Tips

Rick WicklinOctober 22, 2018 0

Transpose blocks to reshape data

A SAS programmer asked how to rearrange elements of a matrix. The rearrangement he wanted was rather complicated: certain blocks of data needed to move relative to other blocks, but the values within each block were to remain unchanged. It turned out that the mathematical operation he needed is called

English

Blogs

Blogs

Programming Tips