How to use two -tail t-test?

I have two set of data (x and y)and I want to show that x is bigger than y by using the two-tail t-test. I know that the if I want to check the tail I need to type 'Tail','right','left', or 'both'. But I do not understand how to show this.

Answer 1

[Star Strider]

If your hypothesis is ‘greater than’ or ‘less than’, use a one-tailed test. If your hypothesis is ‘different than’, use a two-tailed test.

The way to code it (for ttest2), is for example to test that the mean of ‘x’ is less than the mean of ‘y’:

[h,p,ci,stats] = ttest2(x, y, 'Tail','left');

Examine your data and consult the documentation to determine the correct option.

[Weiyan Chen]

If I want to show x is greater than y , I need to use 'right'?

[Star Strider]

Yes!

You are exactly correct in the context of the syntax I posted, with ‘x’ as the first argument and ‘y’ the second.