Difference between means

A teacher teaches pronunciation using several techniques such as drills and songs. She may wonder which technique is more effective, drills or songs. To find out which one is more effective, she needs to conduct experimental research. In this research she asks the following research question:

Is there a difference in pronunciation
between students who are taught using songs
and those who are not?

She has two pronunciation classes and assigns them into two groups:

Experimental group --> taught using songs
Control group --> taught without using songs

At the beginning of the semester, she gives both groups a pronunciation test as a pretest. Then she teaches them pronunciation for one semester. At the end of the semester, she gives them the same pronunciation test as a posttest. The results of the posttest are compared. If the mean of the experimental group is higher than the mean of the control group, she can conclude that using songs is a more effective technique than drills only.

The following table summarises the design of the research.


The teacher can find out whether the difference is significant or not by computing the t value using t-test formula. If her t value is higher than the t value in the table, the difference is significant. However, if her t value is lower than the t value in the table, the difference is not significant.