On Sep 22, 4:41 pm, "
wrote:
I want input on the validity (or not) of the year-over-year statistics
-- that is, the average and standard deviation of many sub-annual
year-over-year data in order to estimate annual statistics.

Well, I am obviously wrong-minded here, at least with respect to the
std dev. Imagine an example where there is significant volatility,
even on annual anniversary dates, but the day-to-day changes almost
identically track the day-to-day changes a year earlier. I might not
be explaining that very well, but the situation arose in a 4-year
subset of the actual data that I am working with. The std dev of the
year-over-year data is deceptively small.