WEATHER IN CRANBERRY CULTURE 85 



For the computation of comparative indices of size, the writer has assumed that 

 the approximate average cup counts of the different sizes in these calculations 

 were as follows: 



The annual indices were computed by multiplying these cup counts by their 

 respective percentages in each year, adding the three products, and dividing the 

 sum by ten. The results appear in Table 1. 



Table 1 gives the following correlations between the several weather elements 

 and cranberry size: 



Correlation Coefficients* 



Early Black Howes 



Hours of Sunshine (December + January). -0.671 ± 0.093 -0.393 ± 0.142 



Temperature (Mean for March) -0.368 + 0.146 -0.606 ± 0.107 



Rainfall (August) -0.320 ± 0.151 -0.629 ± 0.102 



*The coefficients of correlation are minus quantities because cup-counts are inverse measures 

 of size. 



C. D. Stevens Data 



Beginning in 1926, the Boston ofBce of the Bureau of Agricultural Economics, 

 C. D. Stevens in charge, has tabulated data on the size of Massachusetts cran- 

 berries, all varieties together, from growers' reports made in August, October, 

 and November. These three tabulations agree fairly well for the most part, but, 

 all things considered, the one for October seems likely to be rather more accurate 

 than the others. It has therefore been used here and is given in Table 2. Com- 

 parative yearly indices of size for computing correlations were obtained from this 

 tabulation by subtracting the various percentages of "small" berries from their 

 respective percentages of "large" berries. 



Table 2 gives the following correlations between the several weather elements 

 and cranberry size: 



Correlation Coefficients 



Hours of Sunshine— December ' . . . -f 0.442 ± 0.128 



January +0.541 ± 0.112 



December and January together +0.613 + 0.099 



Temperature (mean for March) +0.632 + 0.095 



Rainfall— August +0.384 + 0.135 



September +0.325 ± 0.142 



August and September together +0.497 ± 0.120 



