Untitled - CGIAR Impact

STRUCTURAL CHANGES IN RICE SUPPLY RELATIONS 39
6. Trends in irrigated area and fertilizer consumption in Thailand, 1950-73.
Two specifications for the price variable were used for the area response
function.
• The average price during the previous marketing period, December of
previous year to April of current year, and
• The average price for the previous calendar year.
The two series were deflated either by the price index of nonrice crops or by
the wholesale price index. Each of the four variations of the price variable thus
obtained was tried in estimating the area response function.
The rice price variable used in the yield response function was the average
price during the previous marketing period, December of previous year to
April of current year, deflated by the fertilizer price index. The average price
during the planting period, May to July of current year, was also tried but the
results were inferior and are not reported here.
The price of alternative crops ( Pa ) was included in the area response function
in the form of the price index of nonrice crops (1966-70 = 100). The index