182 WHEAT PRODUCTION IN NEW ZEALAND 
The standard deviations thus found are not directly 
comparable, for the averages of the two series differ. 
I have, therefore, calculated the co-efficient of variation,* 
which is the ratio of the standard deviation to the 
average for each series, multiplied by 100. This co- 
efficient for English prices was 16-64, and for New 
Zealand prices was 18-99, showing a difference of 18 
per cent., for if we represent the co-efficient of variation 
for New Zealand prices as 100, then that for English 
prices is 87. The significance of the result is that the 
degree,of variation in New Zealand prices is greater than 
that in English prices, or, in other words, English prices 
are more consistently near their average than New 
Zealand prices over the period. 
Pursuing the investigation a little further, I have 
calculated the mean yearly movement for the two series 
over the period, that is, the mean of the difference 
between the average annual prices. In the case of 
English wheat, the mean yearly movement was 4:3d., 
and the figure for New Zealand 6-6d., showing a much 
greater average yearly fluctuation in the case of New 
Zealand wheat prices. But the difference is greater 
when we compare these calculations with the average 
annual price for the period, for this figure is 4s. 2d. for 
English wheat, and 3s. 74d. for New Zealand wheat. 
Thus the mean yearly variation in the price of English 
wheat is 8-6 per cent. of the average price; but for New 
Zealand wheat it is 15-2 per cent. of the average price 
for the period. From this calculation, then, the annual 
fluctuations in the price of New Zealand wheat are about 
100 per cent. greater than corresponding fluctuations 
for English wheat prices. 
*See Appendix IIT. 
