Here is a simple plot of the may 2006 data – the box represents the interquartile range (i.e. contains the middle 50% of the price range). The line in the box is the median (50th percentile) – the notch around the median is a statistical confidence interval around the median (95% confidence level).
In this data, you can see that the prices are not distributed evenly – the bottom “half” of the box (25th to 50th percentile, or 2nd quartile) is much narrower than the top “half” or 3rd quartile. So in that month, 50% of the houses sold for between ~1.35 and 3.4 million. *sorry about the funny axis mark for 900K – didn’t feel like fixing it.
If we added another month to this, you could then not just compare the median, but the distribution of prices in those “quartiles” – still not perfect by any stretch, but gives you a little more information than just the median.
[img_assist|nid=3499|title= 92037 – May 2006 Sales Prices|desc=|link=node|align=left|width=466|height=496]
