Subject: Re: Current Price To Peak Book...
"One curve, during periods of rising P/E, is concave upward, and another curve, during periods of falling P/E is concave downward."

Oops. I said that backwards. During periods of rising P/E the curve of forward return versus P/E is concave downward, and during periods of falling P/E the curve is concave upward. Ignoring whether one is in a period of rising or falling P/E gives a plot of forward return versus P/E that is fat in the middle.