358 



MR. S. M. JACOB ON 





Daska. 



Pasrur. 



Zafarwal. 



Raya. 



I. For the 6 months 



April to September . . 



II. For the 6 months 

 October to March 



7182 + -0731 

 •9358 + -01.88 



7076 + -0755 

 •9756 + -0073 



•5700 + -1018 

 •9157+ 0244 



7195 + -0727 

 •9086 + -0263 



In spite of their large probable errors all these coefficients of correlation 

 are significant, and all of them are large enough to make it likely that if a high cor- 

 relation exist between the cropped area and the rainfall in one locality, there 

 will at least be some correlation with the rainfall in an adjacent locality. Thus 

 although considerable local variations of rainfall do occur there are some grounds for 

 thinking that the value of the correlation of the crop in one place with the rainfall 

 in some near place will at any rate approximate to the true correlation with trie 

 rainfall in the place where the crop is grown. The nearer one can get to an estimate 

 of the true mean rainfall affecting a certain area, the higher one would expect 

 the correlation with the crop grown on that area to be, so that even without 

 extending the present method by altering the periods for which the rainfall is taken, or 

 by forming multiple regression equations, the limit of accuracy of prediction is 

 not set by the correlations reached in this paper. 



For the purpose of discussing the effect of the rainfall in the two chief harvests, Kharif 

 (autumn harvest) and Rabi (spring harvest) which occur in the Punjab, it seemed 

 simplest and to a fair extent to be justified by agricultural conditions, to divide the 

 year into two nearly equal divisions comprising respectively the six months of 

 April to September and of October to March, to find the total rainfall in each of these 

 periods and to correlate it with the amount of matured crop in the harvests 

 which ripen towards the close of these periods. These roughly represent too the 

 division of the year meteorologically into the two groups of the South- West Monsoon 

 and the winter rains of the Panjab. 



The notation adopted is as follows : — 



R k = the mean of the total rainfall for the six months April to September, both 



inclusive, for the years 1887 — 1906, measured in inches. 

 ct r - the standard deviation of the above rainfall. 

 v r = the coefficient of variation of the rainfall. 

 C k = the mean area of matured crops measured in acres for the kharif (autumn) 



harvest. 

 °c = the standard deviation of the above area of matured crops. 

 »'c = the coefficient of variation of the above areas of matured crop. 

 v = the correlation of the matured area of crops and the rainfall as defined above. 



