I love this inference from the data.<p><i>An examination of the histogram shows significant seasonal variations. The months July - October show higher than expected births and March - May show the most significant decline in births. Perhaps the most reasonable explanation is that conceptions are up in the months of October through January and down in June through August. You be the judge.</i><p>Wonder if HN has an explanation as to why :)
I wonder what sort of bias might be introduced by starting out with those who bought life insurance? At the least this likely under represents folks at both ends of the wealth spectrum.
There is a noticeable Christmas effect, with birthdays down then and up 9 months later.<p>I wonder if this has changed in more recent years with changes in demographics.