We estimated the generalised translog cost function 24 on data from Ž .
1989r1990 to 1994r1995 using both fixed effect and random effect panel data
procedures. Initial investigations indicated heteroskedasticity, with the variance of
the errors greater for small FHSAs, perhaps because small FHSAs are more likely
to have their administrative costs affected by fixed costs. For the fixed effect
model we therefore apply the White-correction to the standard errors Arellano, Ž
1987 .