# Chapter 1 Statistics With SAS

## Week 1

### One-sample T Test

``````/* This SAS program conducts a one-sample t-test to test whether
the mean sale price of houses in the STAT1.ameshousing3 dataset is equal to \$135,000. */

/* The following line enables the use of ODS graphics,
which allows SAS to generate graphical output. */

ods graphics;

proc ttest data=STAT1.ameshousing3
plots(shownull)=interval
/* This line specifies that the confidence interval should be plotted.
The "shownull" option specifies that the null hypothesis value (in this case,
\$135,000) should be shown on the plot. */
H0=135000;
/* This line specifies the null hypothesis value for the mean sale price. */
var SalePrice;
/* This line specifies that the variable SalePrice should be used for the t-test. */
title "One-Sample t-test testing whether mean SalePrice=\$135,000";
/* This line adds a title to the output, describing the t-test being conducted. */
run;

/* This line clears the title that was added to the output. */
title;
``````

Example 2:

``````/st101s01.sas/ /Part A/
/* This is a SAS program that analyzes the distribution of
two interval variables (BodyTemp and HeartRate) using a
histogram with normal and kernel density plots. */

/* Define a macro variable named interval that contains
the names of the interval variables. */
%let interval=BodyTemp HeartRate;

/* Turn on ODS graphics for generating graphical output,
and specify that only histograms will be displayed. */
ods graphics;
ods select histogram;

/* Use PROC UNIVARIATE to generate a histogram with
normal and kernel density plots for the interval variables. */
proc univariate data=STAT1.NormTemp noprint;
var &interval;
/* Analyze the interval variables specified in the macro variable interval. */
histogram &interval / normal kernel;
/* Generate a histogram with normal and kernel density plots for the interval variables. */
inset n mean std / position=ne;
/* Include the sample size, mean, and standard deviation in the upper right corner of the graph. */
title "Interval Variable Distribution Analysis";
/* Specify a title for the graph. */
run;

/* Reset the title to blank. */
title;

/st101s01.sas/ /Part B/
/* This part of the SAS program tests whether the mean body
temperature is significantly different from the conventional value of 98.6°F. */

/* Use PROC TTEST to perform a one-sample t-test for the BodyTemp variable. /
proc ttest data=STAT1.NormTemp h0=98.6
plots(only shownull)=interval;
var BodyTemp; / Analyze the BodyTemp variable. /
title 'Testing Whether the Mean Body Temperature = 98.6'; / Specify a title for the output. */
run;

/* Reset the title to blank. */
title;``````

### Two-samples T Test

``````/* st101d03.sas */

/* This is a SAS program that performs a two-sample t-test to
compare the mean sale prices of houses with and without masonry veneer. */

/* Turn on ODS graphics for generating graphical output. */
ods graphics;

/* Use PROC TTEST to perform the two-sample t-test. */
proc ttest data=STAT1.ameshousing3 plots(shownull)=interval;
/* Specify the dataset to be used and display a confidence interval plot for the null hypothesis value. */
class Masonry_Veneer;
/* Define the categorical variable Masonry_Veneer as a CLASS variable. */
var SalePrice;
/* Define the variable SalePrice as the continuous variable of interest. */
format Masonry_Veneer \$NoYes.;
/* Specify the format of the values of the Masonry_Veneer variable as "No" or "Yes". */
title "Two-Sample t-test Comparing Masonry Veneer, No vs. Yes";
/* Specify a title for the output. */
run;

/* Reset the title to blank. */
title;
``````

The code above performs a two-sample t-test to compare the mean sale prices of houses with and without masonry veneer. The `plots(shownull)=interval` option displays a confidence interval plot for the null hypothesis value. The `class` statement specifies the categorical variable `Masonry_Veneer` as a CLASS variable. The `var` statement specifies “SalePrice” as the continuous variable of interest. The `format` statement specifies that the values of “Masonry_Veneer” are either “No” or “Yes”. The `title` statement adds a title to the output. The “run” statement executes the PROC TTEST procedure. The final `title` statement resets the title to blank.