Since last October, the consumer price index (CPI) has gone up an annualized 0.7 percent. On an ex-food and energy basis, the number is a little lower, at 0.5 percent. And the Cleveland Fed's trimmed-mean and median CPIs, at 0.7 percent and 0.2 percent, respectively, also put the recent trend in consumer prices in pretty low territory.
And this is before we take into account any potential mismeasurement, or "bias," in the construction of the CPI.
How big is the CPI's bias? Well, in 1996, the Social Security Administration commissioned a study on the accuracy of the CPI as a measure of the cost of living. This so-called "Boskin Commission Report" said the CPI was overstated by about 1.1 percentage points per year. The commission identified several sources of potential bias, but about half of the 1.1 percentage points resulted from new products and quality changes that were slow or otherwise imperfectly introduced into the price statistic.
Since that time, the Bureau of Labor Statistics has initiated a number of methodological changes that have reduced the CPI's mismeasurement. In a 2001 paper, Federal Reserve Board economists David Lebow and Jeremy Rudd put the CPI bias at only about 0.6 percentage points. And again, of this amount, the big share of the bias (about 0.4 percentage points) resulted from the imperfect accounting of new and improved goods.
Now, in an article (available to all in its working paper version) appearing in the latest issue of the American Economic Review, Christian Broda and David Weinstein say the earlier estimates of the new goods/quality bias may be a bit understated.....MORE