Average Returns ... and such

Once upon a time I looked at the calculation of beta and the different numbers you'd
get if you considered the endofmonth prices or one day before the endofmonth or maybe five days before or ...
>Yeah, so?
So, since many investors are interested in the average monthly return of their favourite stock or mutual fund, I was wondering whether that
number changed significantly if you used the monthtomonth returns from, say, midmonth to midmonth or maybe ...
>Yeah, so?
So I have this spreadsheet which looks like this:
Click on the picture to download the spreadsheet
You type in a stock symbol then click a button and get ten years worth of daily prices.
You also get the Average of the Monthly Returns using the prices from endofmonth to endofmonth or a day before that or a day before that or ...
>Meaning the monthly returns using prices from the endofmonth less a few days, right?
Exactly! You also get the Volatility (or Standard Deviation) of those monthly returns.
Note that the very first numbers (coloured red, in the above example) use the endofmonth data.
>So why get worked up about this? I mean, did you expect ...?
I was surprised!
When you read about "historical averages", they may depend significantly upon when they are calculated. Weren't you surprised?
>No!
Suppose average annual returns were calculated considering September prices instead of endofyear prices, or maybe ... ...
>zzzZZZ
Note:
The spreadsheet uses the EOMONTH command ... which is an Excel AddIn.
If'n you haven't added it, then do this:
Tools
then AddIns...
then Analysis Toolpack
then pray ...
