IV estimates preferred; overall IV total is the headline || "the difference between the overall price elasticity estimate of -0.884 obtained using the actual price and the estimate of -0.550 obtained using the instrumental variable technique" (p.551)
Barnes, R., R. Gillingham, and R. Hagemann (1981): “The Short Run Residential Demand for Electricity.” Review of Economics and Statistics 63(4), 541-552