We estimate a generalized linear model to examine adult and teenage cigarette demand. Out analysis focuses on the extent to which excise taxes and regulations restricting smoking in public places affect cigarette consumption. The adult results indicate that the price elasticity of demand is unstable over time, ranging from 0.06 in 1970 to -0.23 in 1985. These estimates are lower than most found in previous studies. The teenage price elasticity does not differ statistically from the estimates for adults. Additionally, regulations restricting smoking in public places have a significant effect on both adult and teenage cigarette demand.

Acquiescence Response Set (ARS), the tendency to agree with questionnaire statements regardless of content, is a source of bias in attitude measurement. ARS is especially problematic in scale development when attitude structure is not well known, because it heightens the correlations among items that are worded similarly, even when they are not conceptually related. This paper describes a partial correlation technique for measuring and controlling for ARS using the method of matched pairs. Respondents (N = 1,351) earned an ARS score from the frequency with which they agreed with pairs of items that are logically opposite. Principal-components analysis was then performed on the firstorder interitem partial correlation matrix, controlling for ARS score. Evidence is presented that this procedure reduces the average interitem correlation among like-worded items, increases the average interitem correlation among un-likeworded items measuring the same concept, and produces a principal components solution that is more interpretable. These conclusions emerge from comparisons with analyses of untransformed attitude scores and attitude scores excluding respondents who demonstrated the greatest acquiescence.Acquiescence Response Set (ARS), the tendency to agree with attitude statements regardless of content, is a potential threat to validity in attitude measurement (Bradburn & Sudman, 1979;Cronbach, 1960). ARS threatens the validity of attitude ratings because it is a source of "correlated errors" that can bias scale scores and produce misleading conclusions about group differences in subsequent analyses (Go've & Geerken, 1977).ARS also poses problems during scale development, when attitude structure is less well known. ARS disguises true relationships between attitude items by falsely heightening the correlations among items that are worded in the same direction at the expense of items

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Technological aspects and early clinical experiences are arousing great enthusiasm over magnetic resonance imaging (MRI). However, influences such as regulation, reimbursement, and increasing competition also are playing important roles in determining the diffusion of this new technology. Of these considerations, competition among providers seems the most important. Competition related to MRI is manifested as direct competition over MRI services, using MRI to improve a provider's strategic position and competition among specialties. In making decisions concerning MRI acquisition and operation, providers are drawing upon their experiences with computed tomography (CT) to help them determine when would be the best time for acquisition, how to decide whether acquisition is appropriate, and how best to acquire, operate, and market the technology.

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