Time‐Limited Counseling Outcome in a Nationwide College Counseling Center Sample

This study examined the dose‐effect relationship between the number of sessions and therapeutic outcome in a large, nationwide counseling center research consortium. A positive relationship was found between the outcome of counseling and the number of sessions attended. The results of this study support the effectiveness of brief psychotherapy.     

Unequal Division of Type I Risk in Statistical Inferences

Introductory statistics texts give extensive coverage to two‐sided inferences in hypothesis testing, interval estimation, and one‐sided hypothesis tests. Very few discuss the possibility of one‐sided interval estimation at all. Even fewer do so in any detail. Two of the business statistics texts we reviewed mentioned the possibility of dividing the risk of a type I error unequally between the tails for a two‐sided confidence interval. None of the textbooks that were reviewed even considered the possibility of unequal tails for two‐sided hypothesis tests. In this paper, we propose that statistics courses and texts should cover both one‐sided tests and confidence intervals. Furthermore, we propose that coverage, at least in two semesters and advanced courses, should also be given to unequal division of the nominal risk of a type I error for both tests and confidence intervals. Examples are provided for both situations.     

Memory priming and trial spacing effects in Pavlovian learning

Conditioning trials that are massed in time produce less conditioning than those that are spaced in time. Four experiments with rat subjects examined whether a recent conditioning trial interferes with conditioning on the next trial by temporarily “priming” information in short-term memory (e.g., Wagner, 1978, 1981). We used appetitive conditioning procedures in which priming trials preceded target trials by 60 sec. When the priming trials were nonreinforced presentations of a conditioned stimulus (CS), the CS had to be the same CS as the one on the target trial to interfere with conditioning. When priming trials were actual CS-unconditioned stimulus (US) pairings, the CS identity did not matter; the US was the event that interfered with conditioning on the next trial. Reinforced trials reduced performance in a way that did not depend on context blocking. The results suggest that CS and US priming effects do contribute to conditioning deficits observed with massed trial procedures. The results are consistent with Wagner’s (1981) “sometimes opponent process,” or SOP, model, although a result that is paradoxical for the model suggests that recent USs may have motivational as well as memory effects.     

Methodological? Or Dialectical?: Reflections of Scientific Inquiry in Biology Textbooks

International Journal of Science and Mathematics Education - Given the importance of cultivating scientific literate societies, the integration of scientific inquiry into school curriculum is key...     

Analysis of a trial-spacing effect with relatively long intertrial intervals

In three experiments with rat subjects, we examined the effects of trial spacing in appetitive conditioning. Previous research in this preparation suggests that self-generated priming of the conditional stimulus (CS) and/or unconditional stimulus (US) in short-term memory is a cause of the trial-spacing effect that occurs with intertrial intervals (ITIs) of less than 240 sec. Experiment 1 nonetheless showed that a trial-spacing effect still occurs when ITIs are increased beyond 240 sec, and that the effect of ITI over 60–1,920 sec on conditioned responding is best described as a linear function. In Experiment 2, some subjects were removed from the context during the ITIs, preventing extinction of the context. Removal abolished the advantage of the long ITI, suggesting the importance of exposure to the context during the long ITI. Experiment 3 still produced a trial-spacing effect in a within-subjects design that controlled for the level of context conditioning and reinforcement rate in the absence of the CS. Overall, the results are most consistent with the idea that adding time to the ITI above 240 sec facilitates conditioning by extinguishing context-CS associations—and possibly context-US associations—that otherwise interfere with CS-US learning through retrieval-generated priming (see, e.g., Wagner, 1981).     

Creative Data in Business Statistics Courses

This paper discusses an innovative approach for using live data generated through student projects or through experiments using student subjects. This live data set, in which the students have a vested interest, becomes the foundation upon which the learning of the statistical concepts is built.     

A Study of the Statistical Inference Criteria: Can We Agree on When to use Z Versus t?

Authors who write introductory business statistics texts do not agree on when to use a t distribution and when to use a Z distribution in both the construction of confidence intervals and the use of hypothesis testing. In a survey of textbooks written in the last 15 years, we found the decision rules to be contradictory and, at times, the explanations unclear. This paper is an attempt to clarify the decision rules and to recommend that one consistent rule be chosen to minimize confusion to students, instructors, and practitioners. Using the t distribution whenever σ is unknown, regardless of sample size, seems to provide the best solution both theoretically and practically.