366 MR. S. M. JACOB ON 



whole, somewhat less than that for the chosen villages, and this is perhaps due to the 

 greater liability to mistakes in classing any particular crcp where only a small propor- 

 tion of that class of crop exists in any definite area, and especia'fy for those villages 

 which largely depend on well water a crop classed as unirrigated may have really 

 received irrigation at critical times from wells, and yet still remain classed as unirrigated. 



It appears probable, therefore, that as a rule the correlation coefficients in the 

 selected villages, that is, in general, the higher values of the coefficients are more pro- 

 bably the true ones. 



Taking each Tahsil separately, the regression equations and the diagrams show- 

 ing the regression lines together with the distribution of rainfall and matured crop 

 wi 1 now be given. 



(i) Tahsil Daska. 

 (a) Kharif. 



The regression equations are :— 



For the regression of crop on rain 



C« = 4i3-53 ^K+11439 

 For the regression of rain on crop 



C,< = 2233-2 Rk- 23744. 



The rainfall from April to September appears to have a high variability from year 

 to year, and the coefficient of variation for the matured area of the crop is nearly 

 twice that of Sialkot and Zafarwal, and consequently *>«• is arge. 



It is probable that for this Tahsil the true mean rainfall over the unirrigated area 

 differs somewhat widely from the value adopted, as, according to Captain Dunlop- 

 Smith, the rainfall varies very greatly from place to place in this Tahsil. He gives 

 the following approximate averages for the total yearly rainfall in each of the four 

 assessment circles : — 



Charkhri II . . . . . . 18" 



Charkhri I . . . . . . 22" 



Aik .. .. .. .. 27" 



Bet Bela . . ... . . 30" 



The Tahsil town of Daska at which the rainfall is taken for the purposes of this 

 enquiry is situated in Charkhri I, and the mean annual value of the rainfall there is 

 about 25", which is just over the mean of the four rainfalls given above. At the same 

 time, as by far the greater part of the unirrigated area of this Tahsil is situated in the Bet 

 Bela assessment circle, the adopted values of the rainfall will probably be too small, in 

 general, while the true mean values will vary from year to year in a different way 

 from the adopted values. Consequently, the value of the correlation coefficient will 

 be different from and most probably less than the value it would have if the true mean 

 values of the rainfall had been ascertained. Figure 9 shows the distribution of rain- 

 fall and matured crop with the regression lines. 



