Author explicitly prefers the non-homothetic specification and states the homothetic estimates are biased || 'the results confirm that the non-homothetical specification has to be preferred to the homothetical one' (p.204); 'the estimated values of the regression coefficients reported in Table 4 [homothetic] are biased' (p.202)
Filippini, M. (1995b): “Electricity Demand by Time-of-Use: An Application of the Household AIDS Model.” Energy Economics 17(3), 197-204