A better argument is that the median skews to the low end during sellers/bull markets. For example, right now when the market is starting to turn to a buyers market, the median priced house may be larger and of better quality than last year. During the peak of the boom, the median priced houses may have been smaller and of less quality. If this is the case, the median could be a good indicator of the rate of price change because even though it overestimates the price during buyers markets, it underestimates the prices during sellers markets.