Raymond Peakl 
41 
accompanying diagram. The unit of a; is 50 grams. The scale of frequency at the 
left of the diagram gives y. 
DiAGBAM I. Showing the distribution of variation in the brain-weight of adult Swedish Males. 
1 I I I I I I I I I 
1075 1125 1175 1225 1275 1325 1375 1425 1475 1525 1575 1625 1675 1725 1775 
416 
The general equation y = y„e~^^''^''', where in this case ?/„ = — - - and cr = 2'1266, 
becomes 3/ = 78 0401 e"''''""'^^^ with the origin at 1400'481. Applying Pearson's 
test of the goodness of fit*, and comparing areas instead of mid-ordinates, as is 
necessary where the number of frequency groups is so small, we get the results 
shown in the accompanying table. The table gives the observed frequencies (m/), 
Grams of 
brain-weight 
Observed 
Calculated 
(m,. - >»,.')" 
Under 1100 
0 
•981 
•981 
1100—1150 
1 
2-9 
r24 
1150—1200 
10 
8-5 
•26 
1200—1250 
21 
20-3 
•02 
1250—1300 
44 
39-0 
•64 
1300—1350 
53 
60-4 
•91 
1350—1400 
86 
75-2 
1-55 
1400—1450 
72 
75-3 
•14 
1450—1500 
60 
60-8 
•01 
1500—1550 
28 
39-4 
3^29 
1550—1600 
25 
20-6 
•94 
1600—1650 
12 
8-7 
r25 
1650—1700 
3 
2-9 
•003 
1700—1750 
1 
•8 
•05 
1750 and over 
0 
•036 
•036 
Totals 
416 
415^817 
11-320 
* Phil. Mcuj. Vol. L. pp. 157—175. 
Biometrika iv 
6 
