Time preferences for the very long term

Many important decisions concern outcomes delayed by decades or centuries. Whereas some economists have argued that inter-generational discount rates should be lower than intra-generational rates, three experiments found that inter- and intra-generational discount rates were quite similar. Experiment 1 found that discount rates for long delays (30-900 years) were lower than those for shorter delays (1-30 years) but that, holding delay constant, discount rates for outcomes occurring to future generations were similar to those for outcomes occurring to the present generation. Experiment 2 compared inter-generational discount rates for three different types of outcomes and found similar discount rates for saving lives, improving health, and financial benefits. Experiment 3 found similar inter-generational discounting of life-saving programs that benefit people close to or distant from the decision maker. These studies indicate that the discount rate applied to outcomes occurring to future generations depends on the length of the time delay but not on other factors.     

Misunderstanding analysis of covariance

Despite numerous technical treatments in many venues, analysis of covariance (ANCOVA) remains a widely misused approach to dealing with substantive group differences on potential covariates, particularly in psychopathology research. Published articles reach unfounded conclusions, and some statistics texts neglect the issue. The problem with ANCOVA in such cases is reviewed. In many cases, there is no means of achieving the superficially appealing goal of "correcting" or "controlling for" real group differences on a potential covariate. In hopes of curtailing misuse of ANCOVA and promoting appropriate use, a nontechnical discussion is provided, emphasizing a substantive confound rarely articulated in textbooks and other general presentations, to complement the mathematical critiques already available. Some alternatives are discussed for contexts in which ANCOVA is inappropriate or questionable.     

A Mixed Methods Study of the Stages of Implementation for an Evidence-Based Trauma Intervention in Schools

A mixed methods study was conducted to examine the implementation process of 26 urban school-based mental health clinics that took part in a training and implementation support program for an evidence-based school trauma intervention. Implementation process was observed using the Stages of Implementation Completion (SIC) measure. Qualitative interviews were conducted with clinic leaders in order to gain insight into clinic processes related to the SIC. Results showed that almost all of the clinics engaged in some activities related to pre-implementation (engagement, feasibility, and readiness), but only 31% of the sites formally started delivering the program to youth. Completing more pre-implementation activities, particularly those related to readiness, predicted program start-up. Qualitative analysis comparing those that implemented the program to those that did not revealed critical differences in decision-making processes, leadership strategies, and the presence of local champions for the program. This study documented the patterns of clinic behavior that occurs as part of large-scale training efforts, suggests some unique challenges that occur in schools, and highlights the importance of engaging in particular implementation activities (i.e., readiness planning, stakeholder consensus and planning meetings) as part of program start-up. Findings indicate that pre-implementation and readiness-related consultation should be employed as part of broad-scale implementation and training efforts.     

Action,inaction, and factors influencing perceived decision making

Two studies examined factors hypothesized to be related to the subjective perception of decision making. A total of 302 introductory psychology students read four hypothetical scenarios that varied on two dimensions: frequency of the behavior and whether the behavior was an action or an inaction (a 2 × 2 design). Subjects rated the scenarios on whether the actor made a decision. In Experiment 1, the frequency of behavior was unrelated to decision making. In addition, actions were given higher decision ratings than inactions in two scenarios, but lower ratings in the other two scenarios. In Experiment 2 the latter discrepancy was explained by ratings of whether the actor behaved thoughtfully rather than reflexively, in that these ratings mediated the action–decision rating relationship. Copyright © 2001 John Wiley & Sons, Ltd.     

Forgetting near‐accidents: the roles of severity,culpability and experience in the poor recall of dangerous driving situations

It is often assumed that real‐life events such as minor road accidents and near accidents will be well remembered. However, surveys of self‐reported accidents suggest that respondents apparently forget approximately one third of their road accidents each year. This paper explores this possibility by looking at memory for the near‐accidents in which drivers are involved. In a pilot study drivers carried microcassette recorders in their cars and reported near‐accidents after each journey. These data confirmed that the frequency of near‐accidents is greatly underestimated when subjects are simply asked to recall them. The main study then compared reports and recalls of over 7000 car journeys from 80 subjects over the course of a year. These included more than 400 reports or recalls of near‐accidents. The influences of the driver's experience, the severity of the near‐accident, and the driver's self‐perceived degree of blame were additionally explored. It is concluded that near‐accidents are generally forgotten extremely rapidly, with an estimated 80% of incidents being no longer reported after a delay of up to two weeks. Serious near‐accidents and those where the driver admitted being to blame in the incident were least likely to be forgotten. Copyright © 2000 John Wiley & Sons, Ltd.     

Intuitive<Emphasis Type="Italic">t</Emphasis> tests: Lay use of statistical information

Normatively, a statistical pairwise comparison is a function of the mean, standard deviation (SD), and sample size of the data. In our experiment, 203 undergraduates compared product pairs and judged their confidence that one product was better than the other. We experimentally manipulated (within subjects) the average product ratings, the number of raters (sample size), and theSD of the ratings. Each factor had two levels selected, so that the same change in statistical power resulted from moving from the low to the high level. We also manipulated (between subjects) whether subjects were given only the product rating data as summarized in a statistical format or the summaries plus the raw ratings. Subjects gave the most weight to mean product ratings, less weight to sample size, and very little weight toSD. Providing subjects with raw data did not increase their use of sample size andSD, as predicted.     

An encounter frequency account of how experience affects likelihood estimation

When making judgments, people often favor information received from a few individual sources over largesample statistical data. Individual information is usually acquired piece by piece, whereas statistical information combines many observations into a single summary. We examined whether this difference in the frequency of encounters affects how data are weighted. In two experiments, subjects read statistical information indicating an event to be rare and contrasting information from individual cases suggesting the event to be common. We controlled whether the individual cases were summarized into a single summary like statistical information, or presented serially, case by case. Subjects’ estimates of event frequencies were higher when the individual cases were presented in serial, rather than summarized, format. A third study demonstrated that subjects treat each data sample as an instance, and do not weight according to sample size. These results support the conclusion that people weight information according to encounter frequency.