How accurate are the prices in the British colonial Blue Books?

ABSTRACT Despite the widespread use of the British colonial Blue Books as a statistical source, there has been little investigation of their reliability. This article compares retail price reports in the Blue Books with annual averages constructed from weekly market reports published in four colonial African newspapers. It finds that the Blue Books can sometimes be an unreliable guide to staple prices, with the median error in the order of 25%, though some series are reasonably accurate and some are very inaccurate. Estimating annual averages was complicated by high price volatility and seasonality. In a simulation, the article shows that colonial officials would have usually needed to gather price quotations reasonably frequently in order to be likely to obtain accurate annual averages. A new effort to find non-official sources for prices, especially for staples, and for the early colonial period, would help to refine estimates of living standards and agricultural market dynamics in colonial Africa.