Not quite normal: Consequences of violating the assumption of normality in regression mixture models     

Lee Van Horn M  Smith J  Fagan AA  Jaki T  Feaster DJ  Masyn K  Hawkins JD  Howe G 《Structural equation modeling》2012,19(2):227-249

Regression mixture models are a new approach for finding differential effects which have only recently begun to be used in applied research. This approach comes at the cost of the assumption that error terms are normally distributed within classes. The current study uses Monte Carlo simulations to explore the effects of relatively minor violations of this assumption, the use of an ordered polytomous outcome is then examined as an alternative which makes somewhat weaker assumptions, and finally both approaches are demonstrated with an applied example looking at differences in the effects of family management on the highly skewed outcome of drug use. Results show that violating the assumption of normal errors results in systematic bias in both latent class enumeration and parameter estimates. Additional classes which reflect violations of distributional assumptions are found. Under some conditions it is possible to come to conclusions that are consistent with the effects in the population, but when errors are skewed in both classes the results typically no longer reflect even the pattern of effects in the population. The polytomous regression model performs better under all scenarios examined and comes to reasonable results with the highly skewed outcome in the applied example. We recommend that careful evaluation of model sensitivity to distributional assumptions be the norm when conducting regression mixture models.  相似文献   

The role of negative priming in preschoolers' flexible rule use on the dimensional change card sort task     

Müller U  Dick AS  Gela K  Overton WF  Zelazo PD 《Child development》2006,77(2):395-412

Four experiments examined the development of negative priming (NP) in 3-5-year-old children using as a measure of children's executive function (EF) the dimensional change card sort (DCCS) task. In the NP version of the DCCS, the values of the sorting dimension that is relevant during the preswitch phase are removed during the postswitch phase. The experiments showed that the NP effect observed in the DCCS decreased during the preschool years, and they clarified the circumstances in which NP occurs. Taken together, the findings suggest that the development of EF in early childhood consists in part in disinhibiting attention to information that has previously been suppressed.  相似文献   

Using and Selecting Graphic Techniques to Acquire Structural Knowledge     

Katherine L. Beissner  David H. Jonassen  Barbara L. Grabowski 《Performance Improvement Quarterly》1994,7(4):20-38

Structural knowledge, the knowledge of relationships between concepts in a content area, is essential for comprehension and problem solving. Learning structural knowledge can be facilitated through learner-generated two-dimensional diagrams of conceptual relationships. These diagrams include networks, concept maps, pattern notes, semantic maps and graphic organizers. In this paper, we describe the characteristics of graphic techniques and the cognitive processes that learners use to construct the diagrams. We then propose a model that can be used to choose between different graphic techniques based upon the cognitive processes elicited by the techniques and the learning outcomes derived from their use.  相似文献   

Grade retention among students with learning disabilities     

Katherine P. Barnett  Harvey F. Clarizio  Karen A. Payette 《Psychology in the schools》1996,33(4):285-293

This study explored the rates of grade retention among children with undiagnosed learning disabilities. During the 1990–91 school year, data were collected on 344 Michigan students who were referred for special-education evaluation due to learning problems. Of the 201 students determined to possess a learning disability (LD), 71.6% had been retained at least once before they were referred for special-education evaluation. Minority and urban LD students were more apt to be retained before being referred for evaluation. Retained LD students were usually one year older than nonretained LD students at the time of special-education referral. Although retention among LD students did not appear to be related to gender or grade placement, retained LD students generally exhibited lower levels of intelligence and weaker skills in reading comprehension, writing, and math at the time of their referral. © 1996 John Wiley & Sons, Inc.  相似文献   

The Impact of Three-Dimensional Printed Anatomical Models on First-Year Student Engagement in a Block Mode Delivery     

Nicholas Tripodi  Kate Kelly  Maja Husaric  Rebecca Wospil  Michael Fleischmann  Susan Johnston  Katherine Harkin 《Anatomical sciences education》2020,13(6):769-777

Student engagement is known to have several positive effects on learning outcomes and can impact a student's university experience. High levels of engagement in content-heavy subjects can be difficult to attain. Due to a major institutional restructure, the anatomy prosection laboratory time per subject was dramatically reduced. In response, the authors set out to redesign their anatomy units with a focus on engaging the learning activities that would increase time-on-task both within and outside of the classroom. One of these curriculum changes was the implementation of a suite of anatomy learning activities centered on sets of three-dimensional printed upper limb skeleton models. A two-part mixed-method sequential exploratory design was used to evaluate these activities. Part one was a questionnaire that evaluated the students' engagement with and perceptions of the models. Part two involved focus groups interviews, which were an extension of the survey questions in part one. The results of the study indicated that the majority of students found the models to be an engaging resource that helped improve their study habits. As a result, students strongly felt that the use of the models inspired greater academic confidence and overall better performance in their assessments. Overall, the models were an effective way of increasing the engagement and deep learning, and reinforced previous findings from the medical education research. Future research should investigate the effects of these models on student's grades within osteopathy and other allied health courses.  相似文献   

Developmental Trends in Sexual Attraction Among Puerto Rican Early Adolescents in Two Contexts     

Katherine S. Elkington  Milton L. Wainberg  Maria Ramos-Olazagasti  Chen Chen  Ana Ortin  Glorisa J. Canino  Hector R. Bird  Cristiane S. Duarte 《Child development》2020,91(3):1044-1055

Sexual attraction (SA), the earliest stage of sexual orientation, is scarcely studied. This prospective study examined, over 3 years, prevalence, changes in SA, and the role of context, among 946 Puerto Rican youth, aged 11–13 years at initial assessment in the South Bronx (SBx), New York City, and Puerto Rico (PR). Overall, 98.1% of boys and 95.3% of girls reported opposite-sex only SA at some point, whereas 13.8% of girls and 12.0% of boys reported any-same SA. Opposite-sex only SA increased over time, whereas other SAs decreased except for any same-sex SA among SBx girls. Girls in the SBx and younger youth in PR reported more any same-sex SA. Context and culture may play a role in the developmental trajectories of adolescents’ SA.  相似文献   

The effect of recovery strategies on physical performance and cumulative fatigue in competitive basketball     

Montgomery PG  Pyne DB  Hopkins WG  Dorman JC  Cook K  Minahan CL 《Journal of sports sciences》2008,26(11):1135-1145

To evaluate the effectiveness of recovery strategies on physical performance during a 3-day tournament style basketball competition, 29 male players (mean age 19.1 years, s= 2.1; height 1.84 m, s= 0.34; body mass 88.5 kg, s= 14.7) were assigned to one of three treatment groups: carbohydrate+stretching (7.7 g kg(-1) day(-1), s= 1.7; 'n = 9), cold water immersion (11 degrees C, 5 x 1; n = 10) or full leg compression garments (18 mmHg, approximately 18 h; n = 10). Effects of the recovery strategies on pre-post tournament performance tests were expressed as the mean change (% +/- standard deviation of the change score). Changes and differences were standardized for accumulated game time, assessed against the smallest worthwhile change for each test, and reported qualitatively. Accumulated fatigue was evident over the tournament with small to moderate impairments in performance tests. Sprint and agility performance decreased by 0.7% (s = 1.3) and 2.0% (s = 1.9) respectively. Vertical jump decreased substantially after the first day for all treatments, and remained suppressed post-tournament. Cold water immersion was substantially better in maintaining 20-m acceleration with only a 0.5% (s = 1.4) reduction in 20-m time after 3 days compared with a 3.2% (s = 1.6) reduction for compression. Cold water immersion (-1.4%, s = 1.7) and compression (-1.5%, s = 1.7) showed similar substantial benefits in maintaining line-drill performance over the tournament, whereas carbohydrate+stretching elicited a 0.4% (s =1.8) reduction. Sit-and-reach flexibility decreased for all groups, although cold water immersion resulted in the smallest reduction in flexibility. Basketball tournament play elicited small to moderate impairments in physical test performance. In conclusion, cold water immersion appears to promote better restoration of physical performance measures than carbohydrate + stretching routines and compression garments.  相似文献   

The effect of self-regulated and experimenter-imposed practice schedules on motor learning for tasks of varying difficulty     

Keetch KM  Lee TD 《Research quarterly for exercise and sport》2007,78(5):476-486

Research suggests that allowing individuals to control their own practice schedule has a positive effect on motor learning. In this experiment we examined the effect of task difficulty and self-regulated practice strategies on motor learning. The task was to move a mouse-operated cursor through pattern arrays that differed in two levels of difficulty. Participants learned either four easy or hard patterns after assignment to one of four groups that ordered practice in blocked, random, self-regulated, and yoked-to-self-regulated schedules. Although self-regulation provided no special benefit in acquisition, these groups showed the most improved performance in retention, irrespective of task difficulty. Although individual switch strategies for members of the self-regulated groups were quite variable, the impact of self-regulation on motor learning remained similar. These findings add to the growing body of literature suggesting that self-regulated practice is an important variable for motor learning.  相似文献   

Tales of the unexpected: coping among female collegiate volleyball players     

Holt NL  Berg KJ  Tamminen KA 《Research quarterly for exercise and sport》2007,78(2):117-132

The purpose of this study was to examine patterns of appraisal, coping, and coping effectiveness in sport. Ten players from a collegiate female volleyball team were interviewed on two occasions, first in the week before a provincial final playoff tournament and in the week following the tournament. Data were transcribed verbatim and subjected to content and idiographic analyses. Athletes generally did not predict or anticipate the stressors they actually experienced during the tournament. Subjective appraisals of effective coping were associated with consistency between proactive and actual coping attempts. Reported effective coping was associated with the attainment of personal performance goals and use of cognitive, behavioral, and emotional coping strategies in the absence of behavioral avoidance. Reported ineffective and partially effective coping was associated with not attaining personal performance goals, and the use of cognitive coping strategies with behavioral avoidance. Finally, older, more experienced athletes reported they coped better than younger, less experienced athletes during the tournament.  相似文献   

Woman,Divided: Gender,Family, and Multiple Personalities in Media     

Katherine J. Lehman 《Journal of American culture (Malden, Mass. : 2003)》2014,37(1):64-73

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