The nonparametric approach to consumer-demand analysis-based on revealed-preference axioms-is reviewed. Particular attention is paid to questions of size and power of tests for consistency of data with the existence of a stable, well-behaved utility function that could have generated the data. An application to Australian meat demand is used to show how these notions can be quantified and how prior information about elasticities, following Sakong and Hayes, may be used to increase the power of the approach.