the number of children to 14 and persons 65 and over was 8,505 in 

 1940, while the number in the 20 to 65 age group was 13,682. Dividing 

 the former by the latter and multiplying by 1,000 gives a dependency ratio 

 of 622 in 1940. This means there were 622 dependents for each 1,000 per- 

 sons in the working age groups. By 1950 the dependency ratio for Belknap 

 County had increased to 678, indicating that there were 56 more dependents 

 for each 1,000 of the working group. 



The dependency ratios for 1940 and 1950 and the change between these 

 dates is given in Table 9 for the state and for each county. Increases were 

 greatest in rural nonfarm and rural farm groups. 



Table 9. Dependency Ratios for 1940 and 1950 by Total, Rural Farm, Rural Nonfarm, and 

 Urban Groups and the Change in Ratio between 1940 and 1950 for Counties and the State 



1 The 1940 definition of urban applied to the male population decreased the in- 

 fluence of Dartmouth College. 



Change in Dependency Ratio Due to Change in Dependents 



An increase in the dependency ratio can occur because of the following: 

 1. An increase in children to 14; 2. An increase in people 65 years and 

 over; 3. A decrease in the working population 20 to 65 years of age; 4. 

 Combinations of 1, 2, and 3. 



In order to measure the relative importance of these categories in the 

 general increases by state and by counties, resort was made to differential 

 calculus.* 



The increase in dependency ratios for each county of the state between 

 1940 and 1950 is given in Table 10. By comparing columns 2 and 3 it is 

 possible to compare the relative importance of a change in the number of 

 dependents with the relative importance of a change in the number in the 

 working age groups. In Belknap county the increment due to a change in 

 dependents was twice as great as that due to changes in the 20 to 64 age 



* X = dependents y = number in age group 20-64 R := Dependency Ratio 



R = f(xy) = X 



aR = j[ ^ = I? 



dx y 5y y^ 



Change in R due to ^x ^ 1 Ax 



y 



Change in R due to Ay = — x Ay 



10 



