Computerized adaptive testing: the capitalization on chance problem

This paper describes several simulation studies that examine the effects of capitalization on chance in the selection of items and the ability estimation in CAT, employing the 3-parameter logistic model. In order to generate different estimation errors for the item parameters, the calibration sample size was manipulated (N = 500, 1000 and 2000 subjects) as was the ratio of item bank size to test length (banks of 197 and 788 items, test lengths of 20 and 40 items), both in a CAT and in a random test. Results show that capitalization on chance is particularly serious in CAT, as revealed by the large positive bias found in the small sample calibration conditions. For broad ranges of theta, the overestimation of the precision (asymptotic Se) reaches levels of 40%, something that does not occur with the RMSE (theta). The problem is greater as the item bank size to test length ratio increases. Potential solutions were tested in a second study, where two exposure control methods were incorporated into the item selection algorithm. Some alternative solutions are discussed.     

Psychosocial predictors of relapse in cocaine-dependent patients in treatment

Relapses in cocaine abusers in treatment are an important problem. The majority of patients are incapable of sustaining abstinence over any length of time. To identify the factors associated to relapses risk in the cocaine use can be an optimal choice to improve the treatment strategies. The aim of this study was to analyze relapse-risk factors in cocaine-dependent patients on treatment. Participants were 102 patients who had begun outpatient treatment at a public health center in Spain. Some functional areas and cocaine use are evaluated for a period of six months. A structural equations model was used to identify possible predictive variables. The results show that social-family environment and economic-employment situation were associated with greater risk of relapse. Likewise, the social-family environment was related to severity of addiction. It is concluded that the incorporation of family intervention strategies and vocational/employment counseling may help to reduce relapse rates in cocaine addicts receiving treatment.     

Civil Engineering at the Crossroads in the Twenty-First Century

The twenty-first century presents a major challenge for civil engineering. The magnitude and future importance of some of the problems perceived by society are directly related to the field of the civil engineer, implying an inescapable burden of responsibility for a group whose technical soundness, rational approach and efficiency is highly valued and respected by the citizen. However, the substantial changes in society and in the way it perceives the problems that it considers important call for a thorough review of our structures, both professional and educational; so that our profession, with its undeniable historical prestige, may modernize certain approaches and attitudes in order to continue to be a reliable instrument in the service of society, giving priority from an ethical standpoint to its actions in pursuit of ??the public good??. It possesses important tools to facilitate this work (new technologies, the development of communications, the transmission of scientific thought.···); but there is nevertheless a need for deep reflection on the very essence of civil engineering: what we want it to be in the future, and the ability and willingness to take the lead at a time when society needs disinterested messages, technically supported, reasonably presented and dispassionately transmitted.     

A more complete task-set reconfiguration in random than in predictable task switch

Three experiments are presented that compare the cost found when switching from one task to another in two different conditions. In one of them, the tasks switch in predictable sequences. In the other condition, the tasks alternate at random. A smaller time cost is found in the random-switch condition when enough preparation time is allowed. Such an effect is due to the random-switch cost continuing to decrease with preparation time after the predictable-switch cost has reached an asymptote. Although the relationship between number of repetitions of one task and time cost is different in the random- and the predictable-switch conditions, only the latter shows the presence of an "exogenous" component of cost. The implications of this finding are discussed in relationship with the usual distinction between an endogenous component of switch cost that is affected by preparation time and another exogenous, residual component (e.g., Rogers & Monsell, 1995). It is proposed that a different kind of task-set preparation is at work when tasks alternate at random.