Posted by **jabrony** on Monday, November 28, 2011 at 1:29pm.

Composite ACT Scores

Non-Athletes Athletes

25 21 22

22 27 21

19 29 24

25 26 27

24 30 19

25 27 23

24 26 17

23 23

a. Test an appropriate hypothesis and state your conclusion. Use alpha = .05 for your test. Show the null and alternative hypothesis, the p-value, your conclusion to reject or not, and finally a summarizing statement regarding your conclusion.

Then create a 90% confidence interval and tell me what it means in terms of the problem.

- statistics (?) -
**PsyDAG**, Tuesday, November 29, 2011 at 11:53am
You have two categories but three columns?

Find the means first = sum of scores/number of scores

Subtract each of the scores from its mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard deviation = square root of variance

Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√n

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.

90% = mean ± 1.645 SD (This is the Z score for .45 from the mean found in that same table.

- statistics -
**jabrony**, Tuesday, November 29, 2011 at 4:46pm
SO FAR I HAVE 9.63 FOR THE 1ST 2 COLUMNS

AND 7.56 FOR LAST COLUMN FOR THE VARIANCES. I GOT Z= .0875

SEDIFF =1.2364 SEm=.6019 for 1st set of #s and SEm=1.08 for 2nd set of #s

is that correct and now what?

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