Posted by Janelle on .
A psychologist wants to estimate the variance of employee test scores. A random
sample of 18 scores had a sample standard deviation 10.4. Find a 90% confidence
2
interval for the population variance. What assumption, if any, have you made in calculating this interval estimate?

statistics 
PsyDAG,
90% interval = mean ± 1.645 SD
SD^2 = variance
Assume normal distribution.