Authors emphasize the average-revenue (P1) own-price estimate as the stable/robust one || 'the estimate of own price elasticity of demand is quite stable when average revenue is the price measure' (p.514); typical-bill estimates 'are statistically insignificant in ten of the sixteen models where they are the price measure' (p.514)
Cicchetti, C.J., and V.K. Smith (1975): “Alternative Price Measures and the Residential Demand for Electricity: A Specification Analysis.” Regional Science and Urban Economics 5(4), 503-516