A test and modification of zipf’s hypothesis for predicting interstate migration

The purpose of this paper is to evaluate the accuracy of Zipf’s hypothesis in estimating interstate migration streams in the United States, and then to determine whether the predictive power of Zipf’s hypothesis can be improved by adding additional variables. The three independent variables in Zipf’s hypothesis accounted for 57 percent of the variation in interstate migration streams in 1935–1940, 61 percent in 1949–1950, and 68 percent in 1955–1960. The addition of per capita personal income of the states of origin and of destination increased the explained variance by only four percentage points in 1935–1940 and by less than one percentage point in 1949–1950 and 1955–1960. Then, the Petersen-Greenwood hypothesis that interstate migration streams in any period are a function of previous flows was tested by adding cumulative lifetime migration as an independent variable. Over 80 percent of the variation in interstate migration streams was explained by cumulative lifetime mobility, as reflected by state of birth data. The conclusion of the study is that the Petersen-Greenwood hypothesis provides a better estimate of interstate migration streams than does Zipf’s hypothesis. Nevertheless, the Petersen Greenwood hypothesis requires further evaluation to determine whether cumulative lifetime mobility is simply a proxy for some other underlying variable and whether it provides accurate estimates of migration streams for other geographic areas.     

Vector representation of migration streams among selected state economic areas during 1955 to 1960

This paper uses in-migration, out-migration, and net migration vectors to measure and portray the migration streams occurring between April 1, 1955, and April 1, 1960, for all persons five years old and over on April 1, 1960, among 38 contiguous state economic areas (SEA's) in Oklahoma, Colorado, Kansas, Missouri, Arkansas, Texas, and New Mexico. Both rectangular and polar coordinates were employed in computing three different types of vector representations. First, migration vectors for each SEA, expressed in total people-miles of in-movement, out-movement, and net movement represent the resultant direction of movement and the total people-miles of movement. Second, in- and out-migration vectors of the total people-miles of movement, with the widths of the vectors drawn proportional to the number of migrants, show the total size of each migration stream for each SEA, the resultant direction of movement, and the distance moved in total people-miles of movement. p ]Third, in- and out-migration vectors of the average distances moved to and from each SEA, with the widths of the vectors drawn proportional to the number of migrants, show the magnitude of movement, the average distance moved per migrant, and the resultant direction of movement. This study shows that migration vectors based upon polar coordinates are more accurate than the migration vectors based upon rectangular coordinates. Also, the in- and out-migration vectors are superior to net migration vectors in representing migratory streams among geographic areas.     

Skeletal biology and the history of Native Americans and African Americans

The authors incorporate data from skeletal remains in an attempt to construct health profiles for the Amerindian population before Columbus's arrival and for the antebellum black slave populations of North America and the Caribbean. They examine the impact of poor nutrition among slaves, as evidenced in bone and tooth samples, on infant and childhood mortality, fertility, and adult mortality. They go on to suggest that the change from a hunter-gatherer life-style to a more sedentary agricultural one resulted in poorer health for the Amerindian population. However, agriculture made soft foods more available, allowing women to wean their children earlier, thus increasing overall fertility.     

The dynamic,complex and diverse living and care arrangements of young New Zealanders: implications for policy

The living arrangements of young people in New Zealand are diverse and often complex. In this article we report the range of care and living arrangements of 209 15-year-old New Zealanders, 47 of whom identified as Māori. These young people were participants in the second generation of a cohort study. Data were collected from their parents via a life history calendar and analysed for variety and consistency of care arrangements, household membership and transitions. Few participants had a consistent pattern of parental care arrangements and most had experienced multiple changes in household composition and frequent changes of address. We conclude that the whānau/family lives of many young New Zealanders are complex and dynamic. These observations contrast with the conventional notions of family life that form the basis for New Zealand’s family policies. We argue that social policies and services impacting on young people need to reflect the lived reality of young people if they are to meet young people’s needs.