Exercise

How different is the ratio?

In the previous exercise, you computed the mean beak length to depth ratio with 99% confidence intervals for 1975 and for 2012. The results of that calculation are shown graphically in the plot accompanying this problem. In addition to these results, what would you say about the ratio of beak length to depth?

Instructions

50 XP

Possible answers

The mean beak length-to-depth ratio decreased by about 0.1, or 7%, from 1975 to 2012. The 99% confidence intervals are not even close to overlapping, so this is a real change. The beak shape changed.

It is impossible to say if this is a real effect or just due to noise without computing a p-value. Let me compute the p-value and get back to you.