In 1853, the First International Statistical Congress unanimously voted a resolution recommending the establishment of population registers in every country:

Such a register has existed in Belgium since 1846. No other country except Sweden, Finland, and Hungary had much experience with such documents in 1853. The resolution was nevertheless ratified in successive International Congresses, but there was no rush to implement it. Several European countries followed suit, including small German states, the Netherlands in 1856, and Italy in 1864. According to a recent United Nations survey, eleven European countries have population registers that trace their origins to the nineteenth century or before: Belgium, Czechoslovakia, Finland, Germany, Hungary, Italy, Luxemburg, the Netherlands, Spain, Sweden, and Switzerland.

Since the publication of V.O. Key’s seminal article, “A Theory of Critical Elections,” numerous scholars have worked to add theoretical depth and analytical sophistication to the study of critical elections. On the latter count, efforts have been ambitious and illuminating; on the former they largely have not. Typologies of elections and descriptions of electoral change have emerged from empirical analyses of aggregate vote data. A variety of techniques ranging from straight forwara t-tests to correlation matrices to a particularly rich analysis of variance approach have been employed to uncover patterns of electoral change. But while a good deal of descriptive, analytical headway has been made, the development of a theory of electoral change has lagged behind.

What theoretical overtures have been made, generally regard critical elections both as the products of prolonged malfunctions in the political system and as the means by which the system begins to correct these malfunctions. According to this view, American electoral politics follows a cyclic dynamic. Critical elections mark the beginnings and the ends of adjoining periods (i.e., party systems) in a repeating cycle of stability, disequilibrium, and adjustment.

Writing more than twenty five years ago, W. S. Robinson assailed the assumption implicit in much empirical work that statistical measures computed for aggregate units—states, provinces, counties, cities, wards, school districts—could be used in place of corresponding measures for the individuals comprising these units. Robinson was not the first scholar to expose the pitfalls of naive inferences from group level data to individual level behavior. But he first brought this problem forcefully to the attention of practicing social scientists. Focusing on the Pearson product moment correlation coefficient (r), Robinson proved that an aggregate level coefficient need not be equal in value to the corresponding individual level coefficient. Blending empirical examples with mathematical demonstration, Robinson showed that when the individual level correlation between being a native American and being able to read was computed for state level percentages of natives and literates, its value changed from .118 to -.526. Thus an investigator relying on correlations computed for the American states would not even correctly assess the direction of the relationship between nativity and literacy. Coining new jargon, Robinson used the term “ecological fallacy” to describe a naive inference from the group to the individual level of analysis.

The reverberations of Robinson’s work are still being felt by those interested in the past behavior of individuals. Historians without access to survey research and experimental techniques must rely on data that have already been collected. Because such data so often pertain to aggregate units, historians frequently must use cross-level inference to estimate the behavior of individuals. Having paid virtually no attention to the methodology of cross-level inference for almost twenty years after the publication of Robinson’s work, historians have suddenly discovered the “ecological fallacy.” Authors dread to see the term “ecological fallacy” scribbled in the margins of their work; to fall victim to this fallacy is to forfeit one’s claim to methodological legitimacy.

Professor Pessen’s recent work on antebellum wealth holding and social structure has been devoted to deflating the “egalitarian myth.” On the basis of data gathered in an extensive study of the rich of four large northeastern cities in the antebellum period, Pessen concludes that the egalitarian hypothesis is not sustained. Wealth was unequally distributed and economic mobility was very limited, in the sense that the rich had rich forbears. Although the origins of great fortunes lay with entrepreneurial types, their descendents gradually withdrew from active business life, maintaining general oversight of wealth that grew almost automatically as the result of fortunate early investments, profitable marriages, and the advantages of membership in a small elite.

The high rate of population turnover in nineteenth-century North American cities no longer requires emphasis. However, students of historical migration have progressed very little beyond merely documenting its existence. As a result, the relationship of social, economic, and demographic factors to migration remains imperfectly understood, and the extent to which rates of population movement varied with economic growth, population size, or other factors still is a matter of conjecture.

In another essay, we began the systematic exploration of population movement through an analysis of patterns in Buffalo and rural Erie County, New York, in 1855. The 1855 New York state census recorded how long each individual had lived in the place in which he or she was enumerated. Using this information, and correcting for mortality, we developed estimates of population persistence and of the determinants of length of residence, which are two conceptually distinct phenomena. We compared both to patterns in Hamilton, Ontario, during the same period and, less systematically, to what historians reported for other places. We concluded that the rate of population persistence in Buffalo was higher than in a number of other cities, and we attributed the difference to the dynamism of the city’s economic life, compared especially to Hamilton in the same years. Nonetheless, despite differences in rates of persistence, the social and demographic correlates of length of residence were strikingly similar in each city and in the countryside as well.

We are all familiar with situations in which we study an historical event, think that we understand it, and then, to our surprise, discover that other historians interpret it quite differently. This happened to me recently, and I should like to describe here what happened, meaning my original understanding and then the interpretations of others who had studied it before me but whose works I had not known about, and then try to draw some conclusions from the experience.