How to know the alpha or critical value of your t test analysis?
The alpha value cannot be determined in the sense that there were a formula to calculate it. Instead, it is arbitrarily chosen, ideally before the study is conducted.
The value alpha = 0.05 is a common choice that goes back to a suggestion by Ronald Fisher in his influential book Statistical Methods for Research Workers (first published in 1925). The only particular reason for this value is that if the test statistic has a normal distribution under the null hypothesis, then for a two-tailed test with alpha = 0.05 the critical values of the test statistic will be its mean plus/minus 2 (more exactly, 1.96) times its standard deviation.
In fact, you don't need alpha when you calculate the p value, because you can just publish the p value and then every reader can decide whether to consider it low enough for any given purpose or not.
How do you decide the critical values(alpha) and analyze with the p value
example: stats.ttest_ind(early['assignment1_grade'], late['assignment1_grade'])
(2 series with score of their assignments)
I understand the concept that if the p value is greater than the alpha value then the null hypothesis cant be neglected.
Im doing a course and instructor said that the alpha value here is 0.05 but how do you determine it.