* THEORY OF STATISTICS.
In calculating the coefficient of contingency (coefficient of mean square
contingency) use the following groupings, so as to avoid small scattered frequencies
 at the extremities of the tables and also excessive arithmetic :—
I. Group together (1) two top rows, (2) three bottom rows, (3) two first
columns, (4) four last columns, leaving centre of table as it stands.
II. Regroup by ten-year intervals (15-, 25-, 35-, ete.) for both husband and
wife, making the last group ‘65 and over.”
III. Regroup by 2-inch intervals, 585-605, etc., for father, 59:5-61°5,
ete., for son. Ifa 3-inch grouping be used (585-615, ete., for both father and
son), the coefficient of mean square contingency is0'465. [Both results cited
from Pearson, ref. 1 of Chap. V.]
IV. For cols., group 1+2, 3+4, . . . , 11412, 13 and upwards. Rows,
0,1+2,3+4,..., 9+10, 11 and upwards.
VI. For cols., group all up to 494'5 and all over 5215, leaving central cols.
Rows singly up 20 : then 20-28, 28-44, 44-56, 56 upwards.

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