Pre- and post-planned evaluation: Which is preferable?

This paper compares the advantages and disadvantages of the “pre-planned” and “post-planned” approaches to evaluating program effectiveness. These evaluative approaches are compared along a number of dimensions which include: (a) Reliability of data and the cost of collecting it; (b) Internal validity; (c) External validity; (d) Evaluation obtrusiveness and threat; and (e) Program goal displacement and program direction. A model designed to help program managers decide when and under what conditions either of these two evaluative approaches should be employed is presented. One major theme throughout this discussion is that despite the growing interest in and use of pre-planned evaluation, the post-planned method has many advantages which often go unnoticed. This paper will help program administrators, planners and evaluators in selecting and implementing these two methods in light of their respective strengths and limitations.     

How beliefs about substance use differ by socio-demographic characteristics,individual experiences,and neighborhood environments among urban adolescents

In this article, we tested a series of Item Response Theory (IRT) models to examine the individual and neighborhood variation in perceived risk along dimensions of substance use (alcohol, marijuana, and hard drugs) and usage patterns (light/experimental use, moderate use, heavy/regular use). Data were gathered from 2266 adolescents aged 9, 12, and 15 residing in 79 Chicago neighborhoods. Developmental patterns for age and amount of use were observed whereby older respondents rated alcohol and marijuana as less harmful compared to the younger respondents, but rated hard drugs as more harmful. Risk perceptions were found to be more closely tied to one's direct experience with drugs rather than a general constellation of beliefs. Neighborhood variation in risk perceptions was also observed for hard drugs and three patterns of use, controlling for characteristics of individual residents. Neighborhoods did not vary in risk perceptions toward alcohol use. Individual-level factors rather than characteristics of the neighborhoods explained the observed neighborhood variation in perceptions toward marijuana use. These findings illustrate the complex links between individual and contextual factors in the development of beliefs about the health risks associated with substance use.     

On the Solution Approach for Bayesian Modeling of Initiating Event Frequencies and Failure Rates

There is a need for plant-specific distributions of incidence and failure rates rather than distributions from pooled data which are based on the "common incidence rate" assumption. The so-called superpopulation model satisfies this need through a practically appealing approach that accounts for the variability over the population of plants. Unfortunately, the chosen order in which the integrals with respect to the individual plant rates λ_i, ( i = 0, 1…, m ) and the parameters a , β of the Γ-population distribution are solved seems to drive the solution close to the common incidence rate distribution. It is shown that the solution obtained from interchanging the order and solving the integrals with respect to the individual plant rates by Monte Carlo simulation very quickly provides the plant specific distribution. This differing solution behaviour may be due to the lack of uniform convergence over (α, β, λ_I, ( i = 1,…, m ))-space. Examples illustrate the difference that may be observed.     

Guidelines for contingency approach to planning

In an earlier article the author discussed the contingency approach to planning as a flexible managerial tool making it possible to find a good fit between the planning process and the organization. In the present article the contingency approach is applied to the product life cycle to show how the different steps in the planning process can be varied as the situation changes. The contingency approach to planning can be used in a similar fashion for a product line, a product division, or the entire organization.