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Rick WicklinAugust 22, 2018 21

A SAS programmer recently asked how to interpret the "standardized regression coefficients" as computed by the STB option on the MODEL statement in PROC REG and other SAS regression procedures. The SAS documentation for the STB option states, "a standardized regression coefficient is computed by dividing a parameter estimate by

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Programming Tips

Rick WicklinAugust 20, 2018 18

Calculators killed the standard statistical table

Video killed the radio star.... We can't rewind, we've gone too far. -- The Buggles (1979) "You kids have it easy," my father used to tell me. "When I was a kid, I didn't have all the conveniences you have today." He's right, and I could say the same

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Data Visualization | Programming Tips

Rick WicklinAugust 8, 2018 0

Plot curves for levels of two categorical variables in SAS

The SGPLOT procedure in SAS makes it easy to create graphs that overlay various groups in the data. Many statements support the GROUP= option, which specifies that the graph should overlay group information. For example, you can create side-by-side bar charts and box plots, and you can overlay multiple scatter

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Analytics | Programming Tips

Rick WicklinAugust 6, 2018 0

How to score and graph a quantile regression model in SAS

This article shows how to score (evaluate) a quantile regression model on new data. SAS supports several procedures for quantile regression, including the QUANTREG, QUANTSELECT, and HPQUANTSELECT procedures. The first two procedures do not support any of the modern methods for scoring regression models, so you must use the "missing

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Analytics | Learn SAS | Programming Tips

Rick WicklinJuly 30, 2018 1

Meaningful names for columns of a design matrix

A programmer recently asked a question on a SAS discussion forum about design matrices for categorical variables. He had generated a design matrix by using PROC GLMMOD and wanted to use the design columns in a subsequent procedure. However, the columns were named COL1, COL2, COL3,..., so he couldn't tell

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Programming Tips

Rick WicklinJuly 25, 2018 0

Color cells in a mosaic plot by deviation from independence

Back in SAS 9.3M2 (SAS/STAT 12.1), PROC FREQ introduced mosaic plots to visualize the joint frequencies in a contingency table. By default, the cells in a mosaic plot are colored according to levels of one of the categorical variables in the analysis. However, in 2013 I showed how you can

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Analytics | Learn SAS | Programming Tips

Rick WicklinJuly 23, 2018 6

How to use the %BOOT and %BOOTCI macros in SAS

Since the late 1990s, SAS has supplied macros for basic bootstrap and jackknife analyses. This article provides an example that shows how to use the %BOOT and %BOOTCI macros. The %BOOT macro generates a bootstrap distribution and computes basic statistics about the bootstrap distribution, including estimates of bias, standard error,

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Programming Tips

Rick WicklinJuly 18, 2018 0

Balanced bootstrap resampling in SAS

This article shows how to implement balanced bootstrap sampling in SAS. The basic bootstrap samples with replacement from the original data (N observations) to obtain B new samples. This is called "uniform" resampling because each observation has a uniform probability of 1/N of being selected at each step of the

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Data Visualization | Programming Tips

Rick WicklinJuly 16, 2018 1

Offset regions: Find all points within a specified distance from a polygon

My colleague Robert Allison recently blogged about using the diameter of Texas as a unit of measurement. The largest distance across Texas is about 801 miles, so Robert wanted to find the set of all points such that the distance from the point to Texas is less than or equal

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Programming Tips

Rick WicklinJuly 11, 2018 2

The probability that two random chords of a circle intersect

In a previous article, I showed how to find the intersection (if it exists) between two line segments in the plane. There are some fun problems in probability theory that involve intersections of line segments. One is "What is the probability that two randomly chosen chords of a circle intersect?"

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