t test for two samples with different sizes

Hi,

Which function should i use if I want to test whether two samples with different sizes have different means? I see many ttest functions in matlab

Answer 1

[the cyclist]

 >> ttest2(x,y)

where "x" and "y" are the vectors of your two samples.

[Shafa-At Sheikh]

As per notes, x and y comes from independent random samples from normal distributions with equal means and equal but unknown variances. What about the case, once the variances are unequal?

Is this function also checking the variances before calculating the significance?

[the cyclist]

The documentation does state that the simplest syntax assumes equal variances. But if you read a bit further in the description, you will see that there is a calling syntax for unequal variances.

Specifically, see the VarType name-value pair