Three conditions under which experiments and observational studies produce comparable causal estimates: New findings from within‐study comparisons

This paper analyzes 12 recent within‐study comparisons contrasting causal estimates from a randomized experiment with those from an observational study sharing the same treatment group. The aim is to test whether different causal estimates result when a counterfactual group is formed, either with or without random assignment, and when statistical adjustments for selection are made in the group from which random assignment is absent. We identify three studies comparing experiments and regression‐discontinuity (RD) studies. They produce quite comparable causal estimates at points around the RD cutoff. We identify three other studies where the quasi‐experiment involves careful intact group matching on the pretest. Despite the logical possibility of hidden bias in this instance, all three cases also reproduce their experimental estimates, especially if the match is geographically local. We then identify two studies where the treatment and nonrandomized comparison groups manifestly differ at pretest but where the selection process into treatment is completely or very plausibly known. Here too, experimental results are recreated. Two of the remaining studies result in correspondent experimental and nonexperimental results under some circumstances but not others, while two others produce different experimental and nonexperimental estimates, though in each case the observational study was poorly designed and analyzed. Such evidence is more promising than what was achieved in past within‐study comparisons, most involving job training. Reasons for this difference are discussed. © 2008 by the Association for Public Policy Analysis and Management.     

Public Perceptions of Benefits from and Worries over Plant‐Made Industrial Products and Plant‐Made Pharmaceuticals: The Influence of Institutional Trust

Although agricultural biotechnology has been a seminal reference point in risk perception studies, public awareness of their exposure to risk deriving from this new technology has been minimal at best. However, recent events indicate there may be growing public concern as new variations of this technology appear. Understanding what drives perceptions of benefits from the third generation of the agricultural biotechnology and what determines public worries are keys for the future of this technology. To this end, this study analyzes survey data from the midsouth region of the United States to construct four separate regression models of perceived benefits from and worries over plant‐made industrial products and plant‐made pharmaceuticals. Findings suggest that while prior experience with and knowledge about agricultural biotechnology has an impact on perceptions of benefits and worries, trust in farmers plays a highly important role in determining perceptions.     

Demographic change and industrialization in germany, 1815–1914

This article analyzes demographic change in Bremen 1815–1914 against the background of changing employment opportunities. Within the pre-industrial employment structure, which still prevailed in the decades after 1850, in-migrants were particularly disadvantaged. When modern industries developed, the situation changed. At the beginning of the twentieth century both male and female in-migrants benefited from a higher life expectancy than the city-born population had. The strong sectoral changes in employment opportunities in Bremen at the turn of the century reinforced the trends towards family limitation. More skilled in-migrants felt the need to adapt their reproductive behavior to facilitate upward social mobility. The article argues for a wider use of archival data, like those used in their study, to explore issues relating to urban demographic change in German cities during industrialization.