Question

How to find confidence intervals LCL and UCL for 90%, 95%, 99% after performing t-test :two sample assuming equal variances? (mean b- mean a)- CI? following (mean b- mean a)+CI? Or ?

Answer 1

We want to find the confidence intervals LCL and UCL for 90%, 95%, 99% after performing t-test :two sample assuming equal variances.

Confidence interval formula for t-test :two sample :-

i.e

[ Where,

Population Mean for 1st sample ,   Population Mean for 2nd sample.

Number of random sample for 1st sample   Number of random sample for 2nd sample.

mean a = Sample Mean for 1st sample , mean b = Sample Mean for 2nd sample.

Sample Standard Deviation for 1st sample ,    Sample Standard Deviation for 2nd sample.

  

Value of

For 90% , ,

For 95% , ,

For 99% ,

Now if we know all the values then we put all the value in the formula and we get confidence interval for t-test :two sample.

[ Note:- Here we consider a = 1st sample , b = 2nd sample. And you get t-critical values from t-distribution probability table. ]