Preface

Richard C. Urbano; Robert M. Hodapp

Since it was begun by Norman Ellis in 1966, the International Review of Research in Mental Retardation has included over 30 volumes produced by three series editors and several editors of individual thematic volumes. Until now, however, no single volume has been devoted exclusively to epidemiology or to developmental epidemiology. Moreover, from among over 250 chapters over four decades, only a few, sporadic chapters of the International Review have been devoted exclusively to epidemiology (Boussy & Scott, 1993; Fryers, 1993).

Beyond its uniqueness, the present volume is also timely in ways that are important to the field of Mental Retardation/Developmental Disabilities (MR/DD). As virtually every chapter illustrates, until recently a fully fledged field of developmental epidemiology of MR/DD was not possible. The technological and theoretical advances were simply lacking, making less feasible specific studies. As a result, one needs to describe the many technical–theoretical advances as well as the best research examples in this area. The current volume is therefore divided into three discrete sections. In Section I an introductory chapter describes the “emerging” nature of the field of Developmental Epidemiology of MR/DD. In Section II, consisting of the volume's next five chapters, contributors review the various methodological, statistical, and theoretical advances that make possible studies in the developmental epidemiology of mental retardation. This section is then followed by the four chapters of Section III. Although employing the latest methods and procedures, contributors of Section III's articles are more focused on their epidemiological findings per se.

As befits a perspective that may be less familiar to most International Review readers, we begin with an introduction. In “Developmental Epidemiology of Mental Retardation and Developmental Disabilities,” Richard Urbano and Robert Hodapp reflect upon the exact meaning of the term “developmental epidemiology of mental retardation.” By way of deconstructing that term's three main components (epidemiology, developmental epidemiology, mental retardation), they highlight the many provocative twists involved in applying a developmental epidemiological perspective to persons with mental retardation. In addition, by comparing developmental epidemiological work as applied to two populations—those with MR/DD versus those with child psychiatric conditions—they illustrate the types of findings that seem imminent in the disabilities field. A general overview, a state-of-the-art description of the present, a peek into the future—this chapter illustrates a subfield at the cusp of providing critical information about both individuals with disabilities and their families.

In “Record Linkage: A Research Strategy for Developmental Epidemiology,” Richard Urbano then tackles the entire issue of linking together various administrative records. Simply stated, it is one thing to have access to records of all of the births, deaths, hospitalizations, or other events in a town, state, or country; it is another—far more informative—thing to link these records together. But how, exactly, does one go about linking a person's birth records to that same person's hospitalization or other records? More generally, how does research using “somebody else's data” compare to smaller scale studies in which the researcher collects his or her own data? Even once one has acquired such large, population-based datasets, what are the steps in the process of going from several very large, raw datasets to cleaned, linked sets that can be analyzed using SPSS, SAS, STATA, and other statistical packages?

Building upon Urbano's chapter, Shihfen Tu, Craig Mason, and Quansheng Song discuss “Second-Order Linkage and Family Datasets.” Second-Order Linkage also uses large-scale administrative databases, but this time the linkage goes beyond the individual. For example, using the mother's social security number and other identifiers, one might be able to construct from a state's Birth Records (and Marriage Records) various families of children born to the same mother. By performing such second-order linkage, researchers are now able to use large-scale administrative records to examine questions involving family genetics, family SES, and parental education levels, health, birth defects, and other issues. Tu, Mason, and Song describe common problems and offer innovative solutions for the many complicated questions involved in second-order, family linkage work.

Russell Kirby follows with his chapter, “Incorporating Geographical Analysis into the Study of Mental Retardation and Developmental Disabilities.” In line with the epidemiologist's focus on “person, place, and time,” Kirby explores issues relating to place—the ways in which where one lives affects one's health, well-being, and chances in life. Although a burgeoning subfield within developmental epidemiology, “geographic information systems” (GIS) have yet to be systematically applied in the study of disabilities. Yet given the ties of disabilities to certain communities (Fujiura & Yamaki, 2000) and the recent interest in social factors related to health and health care among populations with developmental disabilities (Graham, 2005), the time seems ripe to explore the many advantages of spatially-based statistical analyses of large populations.

Jennifer Blackford follows with her chapter on “Modern Statistical Methods Applied to Developmental Epidemiology.” Although most of us are familiar with analyses using standard statistical tests, Blackford relies on the latest statistical and computing advances to address three troublesome issues. The first concerns matching: How does one match on more than a few variables at one time? Noting the usual advice to “just pick two” matching variables, Blackford introduces propensity scores as a technique to match on more than a few variables simultaneously. The second issue concerns the ways in which permutation testing can help offset the limitations involved in using small samples. This “small-sample problem” is ubiquitous in disability studies, particularly when examining rarely occurring conditions. Third, Blackford extends beyond Bonferroni corrections to address the issues involved in multiple (often correlated) outcome variables. Although specifically addressed to developmental epidemiologists examining persons with disabilities, this chapter will be helpful to all researchers examining behavioral issues in groups with MR/DD.

The final chapter in Section II is by Stephanie So, “Economic Perspectives on Service Choice and Optimal Policy: Understanding the Effects of Family Heterogeneity on MR/DD Outcomes.” Although economics is, to most of us, a less well-understood discipline. So illustrates the ways in which economic principles can apply to MR/DD. Her best example involves what might be called “family centeredness.” Across many disability fields (most prominently, early childhood special education), numerous researchers, service providers, and policymakers debate what constitutes a family-centered practice. Few such professionals rely on economic analyses. By analyzing with large-scale epidemiologic data variables such as family resource allocation, competing family values, opportunity costs, and individual family trade-offs, we may be able to determine which practices might be best, for which families or types of families. In performing such analyses, so implicitly asks whether many of our ideas about family-centered practices might be missing the mark.

As the first chapter within the third, “findings” section, it is a pleasure to introduce Rachel Avchen, Tanya Bhasin, Kim Van Naarden Braun, and Marshalyn Yeargin-Allsopp's “Public Health Impact: Metropolitan Atlanta Developmental Disabilities Surveillance Program.” Quite simply, the CDC's MADDS study is among the best available, with findings for over a decade on mental retardation and developmental disabilities (Yeargin-Allsopp, Murphy, Oakley, & Sikes, 1992). More importantly for our purposes, Avchen, Bhasin, Braun, and Yeargin-Allsopp illustrate the care and attention that this group has brought to basic epidemiological issues such as case definition and case finding. Their results are among the best in the field, telling us both how often various conditions occur and which child, parent, or other factors predispose children to such conditions.

Examining “Using GIS to Investigate the Role of Recreation and Leisure Activities in the Prevention of Emotional and Behavioral Disorders,” Tina Stanton-Chapman and Derek Chapman next illustrate how developmental epidemiological principles can be extended in another way. From Bronfenbrenner (1979) on, developmentally oriented researchers have been intrigued by the ecologies of childhood, the ways in which children live within families, which exist within neighborhoods, towns, states, and countries. Yet how such nested circles affect children with disabilities has only begun to be examined. Returning to concerns expressed by Kirby in his chapter on geographical analysis, Stanton-Chapman and Chapman apply the perspective of GIS to the ways that parks and recreational programs can prevent emotional–behavioral disorders. Stanton-Chapman and Chapman have been instrumental in bringing geographical analyses into developmental epidemiological...