Student's t-test

What is standard deviation?

The spread of data around the mean

Excludes extreme values

Why is t-test better than standard deviation?

Comparison of 2 means to see if there is a significant difference

Paired t-test

Comparing 2 sets of related data

Example: Measuring students' test scores before and after a study session. Same people, 2 conditions

Unpaired t-test

Comparing 2 sets of data from different groups

Example: Comparing test scores between 2 different classes of students. Different people, same conditions.

Calculating degrees of freedom

(n₁ - 1) + (n₂ - 1)

Conclusions

There is a significant difference between the means, reject the null hypothesis, accept the alternative hypothesis

There is no significant difference between the means, accept the null hypothesis, reject the alternative hypothesis