Untitled - CGIAR Impact

STRUCTURAL CHANGES IN RICE SUPPLY RELATIONS 37
For the technology variable in the area function, we used the average ratio of
rice yield to maize yield per hectare for the past 5 years ( Y 1 ), which is supposed
to represent the relative level of rice technology ( T ) to the technology of a
major alternative crop ( Ta ). Another technology variable that was used in the
area function was the ratio of rice yield to the average yield of five alternative
crops ( Y 2 ), including maize, coconut, sugar, tobacco, and abaca. As a technology
variable in the analysis of yield function, we tried the ratio of area planted
with MV to total rice crop area ( M ). M is supposed to represent a level of rice
production technology per se. In the yield function, only M was included in the
regression analysis.
A major deficiency in our supply analysis for the Philippines was that we
failed to specify any appropriate variable to represent weather ( W ). In the case
of Thailand, the average rainfall is usually the decisive factor in determining
both area planted to rice and yield. However, in the Philippines, typhoons, usually
accompanied by heavy rainfall, are the major cause of crop damage. Therefore,
it is difficult to select a single factor to represent weather conditions for
rice production. For future improvement of rice supply analysis in the Philippines,
the construction of an appropriate weather index will be a critical step.
Thailand. Aggregate time-series data used for the analysis of rice supply
relations in Thailand cover the period from the 1951-52 crop year to the
1973-74 crop year.
Data on rice and nonrice crop areas, and of rice yield per hectare are plotted
in Figure 4 (the areas are in gross terms, counted twice in case of double-
4. Trends in areas planted to rice and nonrice crops, and rice yield per hectare, in
Thailand, 1951-73.