1 38 Agricultural Research and Productivity 



It was assumed thai long-run-supply curves of winter vegeta- 

 bles were horizontal. Costs of production were estimated for each 

 crop from technical data employing market- wage rates, '^ and de- 

 mand functions were estimated for the marketing season of the 

 plastic-covered crops. Equilibrium quantities were then calculated 

 for each crop. Limited amounts of winter vegetables are obtained 

 from unprotected fields in the warm inner valleys of the country. 

 These quantities were deducted from the equilibrium supply of 

 plastic-covered vegetables. Dividing by average yield, equilibrium 

 areas were projected. These areas are reported in table 7.3, 

 together with the estimated parameters. 



Table 7.3: Equilibrium Estimates of the Diffusion Equation 



Notes: 



Data are the same as in table 7.2. 



*R^ correlation coefficient between the calculated and observed y values. 



k 

 The equation y = i+^^-a' was estimated in the form 



log (kly—\ j = log ft — at + u^. 

 I values in parentheses. 



13. Assuming that the 1968 data used already incorporate fi(w\cx>), and that pro- 

 duction will be concentrated in the hands of producers whose w equals the mar- 

 ket-labor wage rate. 



