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