Xt
is cotton lint export earnings, β0 is a constant, T is trending variable and Ut
is error term. β1 is a trend
coefficient and it is expected to be positive or negative sign.
for years thereafter
DPF = dummy variable for abandonment of producer price fixing, which takes
the value of 0 for period of price fixing, and 1 afterwards
DICA = dummy variable for ICA quotas that takes the value of 0 for years when
quotas were not in force and 1 for years of ICA quotas