I've been playing with OFHEO House Prise Index data this week. It's open access data and can be downloaded into CSV file from OFHEO's web site.
I copied Los Angeles MSA data into this spreadsheet. Columns A-G are original data columns. Columns C and are the year and the quarter. Column is E is HPI.
Columns G-I are HPI "returns" with quarterly, semi-annual and annual sampling. "Return" is r(t) = HPI(t) / HPI(t-lag) - 1, where lag is 1 for quarterly, 2 - for semi-annual and 4 - for annual. At the bottom of the spreadsheet there's standard deviation of these returns: 0.0253, 0.0482 and 0.0969. As you can see, it increases linearly with sampling period length.
This is Argyn's blog. I comment on topics of my interests such as software, math, finance, and music. Also, I write about local events in Northern Virginia, USA and all things related to Kazakhstan