Method of Analysis* 



Population increase or decrease is the result of natural change (birth 

 and death) plus change due to migration. To obtain an estimate of net 

 migration during the period 1940-1950, the population to be expected in 

 1950 was computed for the counties of the state. Births and deaths for 

 each year of the 10-year period were tabulated by county of residence. 

 Deaths were subtracted from births, and the difference added to the 1950 

 population of these counties. The sum represented the expected 1950 popu- 

 lation based on natural increase. The figure was then compared with the 

 1950 census count and the difference measured the extent of net migration 

 and its direction. Because of the small size of the state and the relative 

 degree of urbanization together with the apparent accuracy of the data, 

 no correction was made for under-enumeration or under-registration of 

 births. 



One change in census definition relating to the residence of boarding 

 students has some distorting influence on county data in New Hampshire. 

 In the census of 1940 boarding students were allocated to the county of 

 parental residence. In 1950 these students were counted as residents of 

 the county in which the institution was located. Grafton and Strafford 

 counties, where Dartmouth College and the University of New Hampshire 

 are located, are affected most by this change in method. The more obvious 

 distortion of data due to the change will be footnoted in the appropriate 

 tables. 



Two other changes in census procedure and definition in 1950 from 

 those used in 1940 affected the procedure employed in this study. The 1950 

 definition of rural nonfarm excludes a number of persons who would 

 have been so counted in 1940. The instructions to enumerators were such 

 that the 1950 farm population is somewhat smaller than would have been 

 the case had the 1940 instructions to enumerators been used. These resi- 

 dence categories are only roughly comparable between 1940 and 1950. 

 However, data on rural-urban residence by age by county according to the 

 1940 definition are available in the 1950 census. The closed age groups ex- 

 tend only to those 64 in 1950 and so estimates of migration by these resi- 

 dence categories are limited to the age groups 0-54 in 1940 and 10-64 in 

 1950. This limitation has been adopted in order to provide the best estimate 

 of net migration by age among census residence classes. Migration for the 

 total population is measured for all age groups by county and for the state. 



This study also assesses the influence of migration on the dependency, 

 fertility, and sex ratios which are standard measures of population structure. 



Net Migration by Counties 



The net migration of male and female residents to and from the coun- 

 ties of New Hampshire between 1940 and 1950 is given in Table 1. Some 

 counties showed a greater net loss or net gain than others. Estimates of 

 migration for the state show a net in-migration of females and a net out- 

 migration of males during this 10-year period resulting in a net increase 

 in the state of 1,732. The inclusion of out-of-state students in the 1950 resi- 

 dence categories may well account for this increase so that the true net 

 migration for the state is closer to zero. 



* See Appendix 1. 



