The FREQ Procedure

Example 2: Computing Chi-Square Tests for One-Way Frequency Tables

Procedure features:

PROC FREQ statement option:

ORDER=

BY statement

TABLES statement options:

	NOCUM
	TESTP=

WEIGHT statement

Other features:

SORT procedure

Data set:

COLOR

This example

sorts a data set by geographic region
creates a one-way frequency table for each BY group
orders the values of the frequency table by their appearance in the input data set
suppresses the cumulative frequencies and percentages
computes a chi-square goodness-of-fit test for specified proportions.

The chi-square goodness-of-fit test examines whether the children's hair color has a specified multinomial distribution for two regions. The hypothesized distribution for hair color is 30 percent fair, 12 percent red, 30 percent medium, 25 percent dark, and 3 percent black.

Program

options nodate pageno=1 linesize=80 pagesize=60;

proc sort data=color;
   by region;
run;

proc freq data=color order=data;
   weight count;

   tables hair/nocum testp=(30 12 30 25 3);

   by region;

   title 'Hair Color of European Children';
run;

Output

The frequency table lists the variable values (hair color) in the order that they appear in the data set. The last column lists the hypothesized percentages for the chi-square test. Always check that you have ordered the TESTP= percentages to correctly match the order of the variable levels.
PROC FREQ computes a chi-square statistic for each region. The chi-square statistic is significant at the .05 level for region 2 (p<=.05) but not for region 1, indicating a significant departure from the hypothesized percentages in region 2.

Chapter Contents
Previous
Next
Top of Page