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The matching paradigm can take a number of forms and has been used in many areas of psychology. When participants are asked to match or order sets of objects, researchers must correctly account for the number of matches expected purely by chance. Not accounting for the expected chance matches can lead to incorrectly drawing conclusions based on one's data. This study demonstrated that the z test can be an appropriate and easy test to use in the analysis of matching data from studies that require pairs of objects to be matched with each other. This article proves that in a matching paradigm the expected number of chance matches is 1.0 and the associated variance is also 1.0. The z test is shown to maintain the Type I error close to the nominal significance level when the null hypothesis is true and the sample size is at least 80 or 110. To attain power of .80, a sample size larger than 80 may be needed depending upon the effect size associated with the area of interest and the hypothesized alternative probability distribution. The matching paradigm can take a number of forms and has been used in many areas of psychology. When participants are asked to match, or order, sets of objects researchers must correctly account for the number of matches expected purely by chance. Not accounting for the expected chance matches can lead to incorrectly drawing conclusions based on one's data. This study demonstrated that the simple one-sample z test can be an appropriate and easy test to use in the analysis of matching data from studies that require pairs of objects to be matched with each other. When the null hypothesis is true (i.e., matches are occurring by chance) and the sample size is at least 80 or 110, the z test is shown to maintain the Type I error close to the alpha (significance) level researchers selected. To attain power of .80 a sample size larger than 80 may be needed depending upon the effect size associated with the area of interest. [ABSTRACT FROM AUTHOR]

We focus on the problem of ignoring statistical independence. A binomial experiment is used to determine whether judges could match, based on looks alone, dogs to their owners. The experimental design introduces dependencies such that the probability of a given judge correctly matching a dog and an owner changes from trial to trial. We show how this dependence alters the probability of a successful match of dog to owner, and thus alters the expected number of successful matches and the variance of this expected quantity. Finally, we show that a false assumption of independence that results in incorrect probability calculations changes the probability of incorrectly rejecting the null hypothesis (i.e. the Type I error).

The tobacco industry remains a formidable influence in thwarting tobacco control efforts, in part because industry leaders have raised policymaker and public concern about how tobacco control might negatively impact tobacco farmers. In this study, we interviewed a random, stratified sample of 528 tobacco farmers in the Southeast and 991 U.S. residents about issues related to tobacco farmers. We found that a majority of the U.S. public expressed the belief that U.S. taxpayers subsidized tobacco farmers. This belief, combined with the strong opposition to tobacco farmer subsidies (15 percent thought there should be subsidies), likely play a role in public attitudes toward tobacco farmers. At the same time, however, we found reasonably strong public support for efforts to help tobacco farmers transition to new enterprises, although the public underestimates tobacco farmer interest in diversification. For example, two of three Americans believe that the government should help farmers make a living other than growing tobacco and over half thought that taxpayers should help pay for such programs. These data illustrate potential common ground for elected officials to consider as they attempt to concomitantly address the needs of farmers and the interests of the public. Ultimately, if the interests of tobacco farmers can be made clearly to the general public, and vice versa, pro-health and pro-farmer policies might well become a reality.

Objectives. Use of tobacco and alcohol during childhood predicts heavy use of these substances and use of illicit drugs during adolescence. This study aims to identify developmental correlates of tobacco and alcohol use among elementary-school children. Methods. Cross-sectional surveys were used to measure tobacco and alcohol use, multiple indicators of child competence, parenting behaviors, and parental modeling of tobacco and alcohol use in a sample of 1470 third- and fifth-grade children. Both self-report and teacher-rated assessments were obtained, which allowed collateral testing of study hypotheses. Results. Children's tobacco and alcohol use was strongly related to low scores on several measures of child competence, both self-reported and teacher rated. Children's tobacco and alcohol use was also associated with less effective parenting behaviors and with parental use of tobacco and alcohol. Conclusions. Children's early experience with tobacco and alcohol is associated with weak competence development and exposure to socialization factors that promote risk taking. Interventions to prevent early use of tobacco and alcohol are needed. (Am J Public Health. 1997; 87:359-364)

The vast majority of the safety studies concerning added freeway lanes are based on pre-project versus post-project comparisons of accident rates for the project area only. There are two potential problems with such an approach: First, accurate traffic volume data are required for both the pre-project and post-project periods in order to provide exposure measures in the calculation of accident rates. Experience has shown that the accuracy of traffic volume data is often suspect, particularly in the period prior to reconstruction of a roadway section; repairs to induction-loop counting devices are often delayed to coincide with the construction involving the lane addition. Consequently, in many cases traffic counts in the pre-project period, and sometimes counts in both the pre- and post-project periods, are based on projections from actual counts taken years before. Because added capacity can induce latent demand for travel on the affected section of freeway, the pre-project and post-project periods can be substantially different than predicted by ordinary projection methods. Inaccuracies in the denominators of aggregate accident rate statistics can lead to false conclusions regarding project safety. Comparisons with "control" sections of roadway can be used in the absence of good exposure data. The second problem with aggregate comparisons of accident rates in the project section for pre-project versus post-project periods is that the additional capacity might affect accident risks in adjacent sections of roadway. If this occurs, it is potentially misleading to define the roadway only within the project area as the spatial unit of analysis in the accident rate comparisons. This precludes the ability to analyze possible spatial redistributions of accident locations due to the changes in the characteristics of traffic congestion from the pre-project to post-project periods. Moreover, the selection of the specific area of roadway for project location might be related to its accident history. The treated section of roadway might be a “blackspot" for a number of reasons, but the random nature of accident occurrence is a component in the historical process. It has been shown that a form of selectivity bias called "regression to the mean" (Hauer, 1980a, 1980b) can lead to overestimation of the reductions in accident rates resulting from safety-improvement projects. Such bias can also lead to overestimation of accident migration from treated (project) to non-treated (adjacent) roadway sections (Stein, 1984; McGuigan, 1985). Particularly with regard to added freeway lanes, there might be a migration of accidents from the project area and from upstream of the project area to bottlenecks downstream of the project area, due to the partial relief of congestion in one area and increased traffic flow to another area of congestion. Similarly, there might be a relief of congestion in areas upstream of the project area. Previous studies have recognized the need for "influence" areas (e.g., Urbanik and Bonilla, 1987), but it is difficult to assess the nature of any accident "migration" in terms of aggregate accident rate statistics. The present study attempts to characterize influences through a disaggregate spatial analysis of accident locations.

This paper addresses safety issues associated with High Occupancy Vehicle (HOV) lanes constructed along freeway medians, without physical separation from adjacent traffic. Data associated with operation of such an HOV facility in Southern California are analyzed relative to the pattern of accidents on the facility and the potential role of congestion. Detailed analyses of accident characteristics point out that potentially false conclusions regarding the safety of HOV lanes can be drawn from simple analyses that are based on aggregate measures of accident frequencies and assumed traffic volumes.

This study addresses safety issues associated with the operation of freeway High Occupancy Vehicle (HOV) lanes that are not separated by physical barriers from adjacent, general-purpose traffic lanes. Accident frequencies and characteristics obtained from fourteen months operation of an HOV lane in the greater Los Angeles area, together with similar data for six years prior to opening of the lane, are analyzed to evaluate the safety impacts of the lane operation. The analyses rely on comparisons of accident characteristics associated with the HOV lane to those associated with both temporal and spatial control groups. Changes in accident characteristics are also related to existing patterns of freeway congestion. The results of the case study indicate no adverse effect on safety conditions that could logically be attributed to the HOV operation; all of the changes in the patterns of reported accidents can be explained by changes in the location and timing of traffic congestion. Although no overall change in the exposure to accidents was found, there is a significant migration of accident locations due to the combination of relief of congestion in the project area and a corresponding creation of more severe traffic bottlenecks downstream of the project.

Several issues related to multilevel research and measurement theory are discussed. It was emphasized that questions regarding choice of level of measurement and unit of analysis are less important than the choice of an appropriate statistical model. It was demonstrated that even with an 'error-free' environmental measure not all persons should view the setting in the same manner. The split-sample correlation was clearly shown to have undesirable statistical properties, and the use of standard methods was stressed. Investigators were cautioned to carefully choose a coefficient and were shown that this choice is sometimes tricky. Finally, the analysis of multilevel data using multilevel methods was recommended.

The measurement of the reliability of one's instruments is an important aspect of any scientific undertaking. The use of standard methods for evaluating the reliability of environmental assessment measures has, however, recently come under attack by Richards and his colleagues. This article presents a general view of reliability and the analysis of multilevel data. The meaning of reliability and its usefulness to environmental assessment is discussed. It is shown that standard methods of reliability are useful. The split-sample correlation, which was proposed as an alternative to standard reliability coefficients, is shown not to have the stated properties and cannot be recommended. The intraclass correlation is described and recommended as an alternative to the split-sample correlation. This article concludes with a discussion of the analysis of multilevel data.

Stires's (1982) critique of our study (Levine, McDonald, O'Neal, & Garwood, 1980) and Knowles's (1982) comment on the state of classroom research (both in this issue) are considered. Stires's statement that we interpreted our stud)' as supporting the self-selection rather than the environmental hypothesis is shown to be inaccurate. Instead, we contend that some variables are affected more by location, others by self-selection, and still others by an interaction between the two. Stires's (1980) results are reevaluated and found to be congruent With this View'. We found Knowles's discussion of Griffith's (1921) study and his comments on classroom research provocative, although the relevance to our study seems tangential We fully agree with Knowles about the paucity of theory in this area and suggest several limitations in the existing research that should be dealt with systematically within a theoretical framework. [ABSTRACT FROM PUBLISHER]

Self-awareness has been shown to reduce an individual's susceptibility to bogus bodily state information (that is, the veracity hypothesis). It is not clear, however, whether this effect is mediated by internal cue information or by external demands. In the present study, which minimized the operation of external demand, no support was found for the veracity hypothesis; in fact, self-aware individuals were somewhat less accurate regarding their bodily state than were those not self-aware. [ABSTRACT FROM PUBLISHER]

A two-phase study was conducted to examine the effects of classroom seating position on test scores and participation. When students selected their seats (Phase 1), those in the front performed better on the exam than did those in the rear. There was, however, no effect of proximity on participation. When students were randomly assigned to seats (Phase 2), there were no differences in test scores as a function of proximity; however, students in the front of the class participated more than did those in the rear. These results imply that the relationship between seating position and grades is mediated by self-selection processes, while participation is influenced by seat location per se. [ABSTRACT FROM PUBLISHER]