412 THEORY OF STATISTICS. 
in theory of correlation, 177, 204, tion, 188, 252, 333 ; law of error 
205, 319-320; of generalised de- (normal law) and frequency- 
viations (arrays), 234, 236-237 ; curves, generally, 273, 314, 393 ; 
other names for, 144 ; of a sum theory of sampling, probable 
or difference, 210-211 ; effect of errors, etc., 273, 354 ; dissection 
errors of observation on, 211; of of normal curve, 315. 
an index, 214-215; of binomial Elderton, BE. M., refs., variate differ- 
series, 299-300. For standard- ence method, 392. 
deviations of sampling, see Error,  Elderton, W. Palin, refs., calculation 
standard. of moments, 154 ; table of powers, 
De Vries, H., data cited from, 102. 358; tables for testing fit, 354, 
Dice, records of throwing, 258-259, 358; Frequency Curves and Cor- 
(qu. 1, 2, 3) 274, 371 ; testing for relation, 154, 361, 397. 
significance of divergence from  Engledow, F. L., refs., yield trials, 
theory, 267, 373-376 ; refs., 273. 396. 
Dickson, J. D. Hamilton, normal Error, law of ; errors, curve of.: See 
correlation surface, 328. Refs. Normal curve. 
normal correlation, 333. — mean, 144. 
Difference method in correlation, — mean square, 144. 
197-199 ; refs., 226, 252, 392. — of mean square, 144. 
Diphtheria, ages at death from, — probable, in sense of semi-inter- 
table, 98 ; diagram, 97. quartile range, 147 ; in theory of 
Discounts and reserves in American sampling, 310-311. For general 
banks, table, 163 ; diagram, facing references, see Error, standard. 
166. — standard, def., 267 ; of number 
Dispersion, measures of, 107, 133— or proportion of successes in 7 
156 ; unsuitability of range as events, 256-257 ; when numbers 
a measure, 123; relative, 149; in samples vary, 264-265; when 
refs., 154. See Deviation, mean ; chance of success or failure is 
Deviation, standard ; Quartiles. small, 265-266; of percentiles 
Distribution of Frequency. See (median, quartiles, ete.), 337-341 ; 
Frequency-distribution. of arithmetic mean, 344-350 ; of 
Doodson, A. T., refs., mode, median, standard-deviation and coefficient 
and mean, 390. of variation, 351; of coefficients 
Duckweed, correlation between, of correlation and regression, 352 ; 
mother- and daughter-frond, 185— of correlation-ratio and test for 
187. ; linearity of regression, 352 ; refs., 
Duffell, J. H., ref., tables of gamma- 273, 289, 354-355, 395. See also 
function, 358. Sampling, theory of. 
Duncker, G., relation between geo-  — theory of. See Sampling, theory 
metric and arithmetic mean (qu. of. 
9), 156. Estates, annual value of. See Value. 
Everitt, P. F., refs., tables for calcu- 
EArNINGS of agricultural labourers : lating Pearson’s coefficient for a 
calculation of standard-deviation, fourfold table, 358. 
135-137 ; mean deviation, 145; Exclusive and inclusive notations for 
quartiles, 147; correlation with statistics of attributes, 14-15. 
pauperism and out-relief, 177-181, Explosions in coal-mines, deaths 
constants, (qu. 2) 189, 239; dia- from, as illustrating theory of 
gram, 180 ; by partial correlation, sampling, 288. 
239-247 ; diagram of model, 246.  Eye-colour, association between 
Edgeworth, F. Y., dice-throwings father and son, 34-35, 38, 70-71 ; 
(Weldon), 258 ; probable error of association between grandparent, 
median, etc., 344. Refs., Index- parent, and child, 46-48, 53-54 ; 
numbers, 130-131, 391 ; correla- contingency with hair-colour, 61, 
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