In Chapter 2, the author states:

"With regards to the above plot, we are still pretty uncertain about what the true frequency of cheaters might be, but we have narrowed it down to a range between 0.05 to 0.35 (marked by the solid lines)."

I am trying to understand how these values (0.05 to 0.35) are calculated. I initially thought they were derived from the Highest Density Interval (HDI), but the HDI is from 0 to 0.42.

Can someone provide an explanation of how to calculate the 0.05 to 0.35 interval mentioned in the book? Any pointers or detailed steps would be greatly appreciated.

Thank you!