To ascertain if there is a significant difference between the means of two groups, a t-test is a statistical hypothesis test. When comparing the means of two groups to check if they statistically differ from one another, it is frequently utilised. To determine the statistical significance of the difference between the groups, the t-test generates a t-statistic, which is then compared to a critical value from the t-distribution.
There are several types of t-tests, and the choice of which one to use depends on the nature of your data and research question:
- Independent Samples T-Test: This sort of t-test is utilised when comparing the means of two independent groups to see whether there is a statistically significant difference between them. To compare the test results of two separate classes of students, for instance, you may use an independent samples t-test.
- Paired sample T-test-
When two related groups are involved, the paired samples t-test is performed to see if there is a statistically significant difference between the means of the paired observations. For instance, you may compare the test results of the same group of students who got an intervention before and after using a paired samples t-test.
Example in SAS
/* Sample data */
data mydata;
input Group $ Score;
datalines;
A 75
A 80
A 85
B 90
B 95
B 100
;
run;
/* Perform an independent samples t-test */
proc ttest data=mydata;
class Group;
var Score;
run;
In this illustration, the continuous variable you wish to compare is Score, and Group is a categorical variable that represents the two groups. The grouping variable is specified by the CLASS declaration, and the variable you want to compare is specified by the VAR statement.