A3 is the author's chosen residential specification (heteroskedasticity-weighted, black-coal-augmented); the -0.554 own-price elasticity is the single headline residential elasticity computed at sample means || 'On the basis of equation (A3) the estimated price and expenditure elasticities of domestic electricity demand, calculated at the sample means, are -0.554 and 0.926 respectively.' (p.10)
Hawkins, R.G. (1975): “The Demand for Electricity: A Cross-Section Study of New South Wales and the Australian Capital Territory.” Economic Record 51(133), 1-18