1. Menstrual cycle length. Problem 3 calculated the mean length of menstrual cycles in an SRS of 9 women. The data revealed days with standard deviation s = 2.906 days.
2. Calculate a 95% confidence interval for the mean menstrual cycle length.
3. t8,0.975 = 2.306
4. 95% CI = = 27.78 (2.306)(0.09687)
5. = 27.78 2.23 = (25.5 to 30.0) days
6. Based on the confidence interval you just calculated, is the mean menstrual cycle length significantly different from 28.5 days at = 0.05 (two sided)? Is it significantly different from = 30 days at the same -level? Explain your reasoning. (Section 10.4 in your text considered the relationship between confidence intervals and significance tests. The same rules apply here.)
7. Question is: How to wrap my head around CI and the significance of mean?