I am confused by the explanation of the notches on box plots. Matlab help indicates that the notches are at q+/-1.57*iqr/sqrt(n), where q is the median and iqr is the interquartile range. It is then stated that this is equivalent to the 5% confidence limits on the median. From what I learned about statistics a multiplier of 1.96 would be the 95% confidence limits on the median, so I'm not sure 1) why matlab chose to use the 1.57 multiplier, 2) where the 5% confidence limit result comes from in using this multiplier. Looks more like 67% conf limits, or equivalent to 1 sigma for a normal distribution? Is there a way to get box plots to make notches at the 95% confidence limits of the median (ie, using the 1.96 multiplier)?
Thanks for clarifying.