Course Content

Learning Statistics with Python

The task of the t-test is to determine whether the difference between the two samples' means is significant. What should we take into consideration to perform it?

- Obviously, we should consider the
**difference between the means**itself.

- As shown in the image below, the
**variance**matters too!

- Also, the
**size**of each sample should be considered.

To account for the **difference between the means** we just take that difference.

The story is not that simple with **variance**.

T-test assumes the variance to be the same for both samples. We will talk more about it in the *t-test assumptions* chapter. To estimate the variance from two samples, the **pooled variance** formula is used.

And to account for the **size**, we need sample sizes:

Let's put it all together into **t statistic**.

You may have noticed that sample sizes are not used most intuitively. But this way **t** follows the **t-distribution**, as will be discussed in the next chapter.

What properties of samples does t-test consider?

## Select a few correct answers

Section 6.

Chapter 3