24° THEORY OF STATISTICS, 
like the bottom and three sides of a box. Supposing the open 
side to face the observer, a scale of pauperism is drawn vertically 
upwards along the left-hand angle at the back of the “box,” the 
rf “Il | | fl WT fra : 
= Ea 
- > 
D 
Fie. 456.—Model illustrating the Correlation between three Variables: (1) 
Pauperism (percentage of the population in receipt of Poor-law relief); 
(2) Out-relief ratio (numbers given relief in their homes to one in the 
workhouse) ; (3) Average Weekly Earnings of agricultural labourers, 
(data pp. 178 and 189). A, front view ; B, view of model tilted till the 
plane of regression for pauperism on the two remaining variables is scen 
as a straight line. 
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