Hi guys, I need some help with this one ( mainly "1" and "2" ):
A research check tails of 40 cats. these are the results:
average s.d n
Males 190 15 22
Famales 180 12 18
1. check the hypothesis that the tails of the males are longer, with significant level of 10%.
2. what is the significant of the result ? ( p value )
3. build a confidence interval of 90% to the mean difference
You should be pooling the two sample variances if you're using 40-2 degrees of freedom.
That means you are assuming equal varainces.
Otherwise if you use the above standard deviation you need Satherwaithe's approximation for the degrees of freedom.
I would do a one sided test where Ha is the claim that the male's tail is longer on average.