Stats: T-tests and degrees of freedom...?

2 ⤊

Stats: T-tests and degrees of freedom...?

I'm using an online calculator to run a series of t-tests. The calculator requires a mean, an SD and N for both groups, no problem. However, when I get my T-score it also gives me the degrees of freedom. I would expect a consistant DF of 209 since I'm working with an N of 210 (both groups combined) but the program is giving me DFs ranging from the 20s to the upper hundreds. Am I missing something here? Can you help me understand?

2007-03-02 01:59:55 · 2 answers · asked by hot carl sagan: ninja for hire 5 in Science & Mathematics ➔ Mathematics

Figured it out

2007-03-02 02:07:26 · update #1

2 answers

Wookies!

2007-03-02 02:19:15 · answer #1 · answered by Anonymous · 1⤊ 0⤋

practically when degree of freedom is high as 200 the destribution can be approximated to standard normal distribution, so find the t score using normal distribution,

2007-03-02 10:13:14 · answer #2 · answered by san 3 · 1⤊ 0⤋