GENERAL CONDITIONS IN NEW ZEALAND 43 
STANDARD DEVIATION OF RAINFALL = a 
= WV 49.02 
= 4.36 
STANDARD DEVIATION OF YIELD = erat 
= WV 21.68 
= 4.65 
2c + 203.41 
CO-EFFICIENT OF CORRELATION = “Saya gana ee 
+ .250 
1— (.250)?2 x 6745 
v 40 
= al 
PROBABLE ERROR 
between rainfall and yields in New Zealand as far as it 
is possible with the information I have been able to 
collect. 
The method adopted has been to ascertain the co- 
efficient of correlation between yields and rainfall over 
a series of years. Rainfall records at Lincoln meteoro- 
logical station were used, and the rainfall for the seven 
months (May to November) was taken as the most 
important. But it is doubtful whether it would not 
have been more appropriate to have taken the rainfall 
from August to December, as it is during these months 
that the crop is really growing and ripening. In the 
opinion of many persons who are interested in agri- 
culture, the rainfall for May and June is not of great 
importance; for the ground is regarded as being moist 
enough during those months whatever rainfall is ex- 
perienced, and provided a good spring rainfall is 
forthcoming, a good yield should follow in any case. 
But this opens up a further line of investigation, for 
which time is not available at present. The principle 
is the same, and the only difference would be to take 
rainfall statistics for the months August to December, 
and then proceed along the same lines as are here 
indicated. 
