A Comment on Udry's “Increasing Scale and Spatial Differentiation”

et us say at olnce that we welcome the two tests of the Slhevky thieory that J. J iRichard Udry has made. \Ve are indebted to him for the ingenluity he lhas slhown and the work he lhas dolne in the organization and initerpretation of his data. We have a number of disagreemenlts with lis procedures and conclusions, lhowever, somie admittedly picayuine, but we will limit ourselves here to just a few commiients and questions. 1. Udry's longitudinal test of increasing scale, usingtilmie series data for the Ulnited States, results in some support for and somie negationof the lhypothesis-about three and four-fiftlhs for and three anld one-fifth against of the seveni test variables Udry uses. The onle-fifth against caln be quickly disposed of: the increase in the birth rate after 1940. This inicrease is perfectly consistenit with Shevky and Bell's earlier statemiienlt: "Inlstead of seeing the urban process as inevitably producing lower birtlh rates . . . we prefer to suggest that relatively fixed preferelnce alternlatives may exist withliii the fraimiework of nmodern society. Silnce the pressure of the populationl oln the foocl supply lno longer explainis population growtlh in suclh societies as tlhe Unlited States, otlher explalnatory concel)ts are nieeded. We would . postulate a ran,-e of available clioices includilng, at least, faimiilislmi, vertical social imobility, alid consumption."1l This social clhoice hypothesis is a fundamiiental aspect of the tlheory andl precludes the precliction of the necessary contilnuationl of the lowering of birth rates as societies increase in scale. In fact, it las been subjected to aclclitiolnal test alnd elaborationl (althoughI not with longitudinal data).2 Udry realizes that the mobility measure, results fromi wvlhiclh also appear contrary to the theory, is not fully acceptable when he notes that "an index more sensitive to smaller moves mighlt lhave showvn an association between scale anid mobility." But it has the furtlher difficulties of iglnoring international movemenits by omitting the non-native population, excluding mnigration witlin the samie state, anid not miieasuring the miultiple mioves of the samiie individuals. The data on percent in the labor force do not appear to support Shevky and Bell's statemenits, althoughI these data are, of course, confounded by a number of different trends (e.g., percent of womien in the labor force, changing fertility, patterns of internationlal mnigration, increasinig education of young adults, etc.). A better test of the theory, as formulated by Slhevky anld Bell, would have been an examllinatioin of the clhanging age distribution and especially the ratio of aged depenldents to clhildreln. As is well knowln, suclh statistics support the genelralizatiolns of aln increasing proportion of persons in the "active" population (say roughly fromii 15 to 64 years of age) andcI of a gradual reduction in dependent clhildren anld inlcrease in older aged persons through 1940 for the United States.3 To the extent to wliclh increasilgbirtlh rates can explain the shift away from these trenlcls sinlce 1940, the tlheory, thirough the inldividual social clhoice lhypotlhesis, canl accounlt for the facts, but if collective policies are involved, suiclh as American immllligr atioln policy, tlhen somiie explicit miiodification of the tlheory may be in order. The final variable whliclh fails to support the tlheory is the percentage of building starts wvliclh are single famiiily dlwellings. This variable is subject to the saml-e criticismll we have 1 Eshref Slhevky and Wenidell B1ell, Soci(il Ar-ea A nalvsis (Stanford: Stanford University Press, 1955), p. 12. 2 Wendell Bell, "Familismii alnd Suburbanization: One Test of the Social Choice Hypotlhesis," Rural Sociology, 21 (September-December 1956), pp. 276-283; revised and elaborated under the title, "Social Choice, Life Styles, and Suburban Resiclelce," in WVilliam Dobriner (editor), The S.lulrban Conin-munity (New York: Putlnam, 1958), pp. 225-247. 3 For exalmiple, see Williamii Petersell, Popitulctioit (New York: The Macmiiillani Co., 1961), pp. 76-83.