THE FIRST-BORN'S HANDICAP 



Accumulation of Statistics Appears to Show That Eldest Members of a Family 

 Are "Weighted" — Possible Explanations of the Fact. 



Review Of a Book by Karl Pearson 

 Director, Gallon Laboratory for National Eugenics, University of London. 



WHEN Karl Pearson, in 1907, 

 published statistics which 

 appeared to show that the 

 first and second-born in 

 any given fraternity or sibship were 

 more likely to be attacked by tuber- 

 culosis and were, therefore, presumably 

 constitutionally inferior, in that respect 

 at least, to their later brothers and 

 sisters, his conclusions did not lack 

 assailants. The succeeding years have 

 seen a good deal of work on the problem, 

 the latest contribution being from 

 Pearson himself.^ Before its contents 

 are considered, it may be of interest to 

 recall Pearson's original contribution, 

 which Schuster sums up as follows : 



"The Crossley Sanatorium at Frod- 

 sham is filled with lower middle-class 

 and working-class patients suffering from 

 consumption, who come mostly from 

 Manchester and, to a lesser degree, 

 from Liverpool and its neighborhood. 

 From the records kept of the family 

 histories of the patients it is possible to 

 tell how many came in each particular 

 place in their families. It was then 

 found that of 381 jjatients, 113 were 

 first-born and 79 second-born. When 

 the jjatients and all their brothers and 

 sisters, living or dead, are taken to- 

 gether, it was found that in the 381 

 families there were 381 first-born and 

 366 second-born. Dividing these num- 

 bers by the average number of children 

 per family, one arrives at the number of 

 first-born and second-born which, ac- 

 cording to the theory of probability, 

 one would expect to find in a sample 

 made uj) by i)icking one child at random 

 from each family. The numbers are 67 

 and 64. The 381 sanatorium patients 



' On the Handicapping of the First-born, by 

 four diagrams, pp. 68, price two shillings net. 

 National Eugenics, Eugenics Lecture Series X. 

 W., 1914. 



332 



may be regarded as a sample selected 

 by consumption, one from each family 

 and among them the corresponding 

 numbers are 113 and 79 — that is to 

 say, about 1^ times as many first-born 

 and \}/i times as many second-born, as 

 in the random sample of the same size. 

 As the differences are too large to be 

 due to chance, they appear to show 

 that consumption does not pick at 

 random, but selects more particularly 

 the first-born and second-born. With 

 regard to the third and later born 

 members the differences were reversed, 

 there being fewer of these among the 

 patients than would be the expectation 

 if the latter were drawn by chance, one 

 from each family." 



Pearson contented himself with pre- 

 senting the statistics, not attempting to 

 explain them. His critics attacked 

 them from two sides — first on purely 

 statistical grounds, and second, by 

 attempting to explain them away. 

 Pearson's new paper on the subject is 

 devoted largely to refuting those of his 

 critics who attacked him on purely 

 statistical grounds; and into this aspect 

 of the case the reviewer will not go. 

 Those who are interested in the mathe- 

 matical theories involved may consult 

 the original paper. Pearson also simis 

 up the evidence in sup])ort of his con- 

 tention, however, and brings forward 

 new data which equally tend to indicate 

 that the first-l)orn members of a popula- 

 tion are weighted. It may be of 

 interest to review this data. 



division of the problem 



There are, it is evident, several ways 

 in which a statistically demonstrated 



Karl Pearson, F. R. S. With frontispiece and 

 University of London, Oalton Lal)oratory for 

 London, Dulau and Co. Ltd., 37 vSoho Square, 



