95% confidence interval

#1
I'm not sure how to construct a 95% confidence interval for a one tailed test.
I know that for a two tailed test, it's just the critical value...
 

JohnM

TS Contributor
#2
For a one-tailed confidence interval, it's:

upper --> sample mean + Z(alpha) * s/sqrt(n)

lower --> sample mean - Z(alpha) * s/sqrt(n)


For a two-tailed interval, it's:

sample mean +/- Z(alpha/2) * s/sqrt(n)