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Mixed-model Analysis (mixed-model + analysis)
Selected AbstractsHuman sex differences in d -amphetamine self-administrationADDICTION, Issue 4 2010Andrea R. Vansickel ABSTRACT Women and men may respond differently to the effects of stimulants such as amphetamine and cocaine. Aim In order to assess potential sex differences in the reinforcing effects of d -amphetamine, a retrospective-analysis was conducted on data collected from three studies that employed similar d -amphetamine self-administration procedures and used identical subject-rated drug-effect measures. Methods Data from 10 women and 15 men were included in the analysis. In all studies, participants sampled placebo, low (8,10 mg) or high (16,20 mg) dose oral d -amphetamine. Following sampling sessions, participants worked for capsules containing one eighth of the previously sampled dose on a modified progressive-ratio schedule of reinforcement. We hypothesized that women and men would be differentially sensitive to the reinforcing effects of d -amphetamine. A two-way mixed-model analysis of variance (sex and dose) and planned comparisons were used in the statistical analyses. Results The low dose of d -amphetamine functioned as a reinforcer in women, but not men, whereas the high dose of d -amphetamine functioned as a reinforcer in men, but not women. Men self-administered significantly more capsules under the high dose condition than women. Conclusion The results of this study suggest that men are more sensitive to the reinforcing effects of a high dose of d -amphetamine than women. Future research is needed that determines prospectively the reinforcing effects of weight-adjusted doses of d -amphetamine in women and men while controlling for menstrual cycle phase. [source] Measuring Children's Self-Efficacy and Proxy Efficacy Related to Fruit and Vegetable ConsumptionJOURNAL OF SCHOOL HEALTH, Issue 2 2009Karly S. Geller MEd ABSTRACT BACKGROUND:, Social cognitive theory describes self-efficacy and proxy efficacy as influences on fruit and vegetable consumption (FVC). Proxy efficacy was defined as a child's confidence in his or her skills and abilities to get others to act in one's interests to provide fruit and vegetable (FV) opportunities. The purpose of this study was to develop a scale assessing children's self-efficacy and proxy efficacy for FVC at after-school programs and at home. METHODS:, Elementary-aged children (n = 184) attending 7 after-school programs completed a self-efficacy questionnaire relevant to FVC. Questionnaire validity was investigated with exploratory factor analysis and mixed-model analysis of covariance. Internal consistency reliability and readability were also assessed. RESULTS:, The questionnaire assessed 4 constructs: self-efficacy expectations for fruit consumption, self-efficacy expectations for vegetable consumption, proxy efficacy to influence parents to make FV available, and proxy efficacy to influence after-school staff to make FV available. Children perceiving FV opportunities in after-school had greater self-efficacy expectations for FVC and greater proxy efficacy to influence after-school staff compared to students who did not perceive FV opportunities. Children attending schools of higher socioeconomic status (SES) and less diversity were more confident they could influence their parents to make FV available than students attending lower SES and less diverse schools. Adequate internal consistency and test-retest reliabilities were established. CONCLUSIONS:, Self-efficacy is a multicomponent construct that can be assessed in children using the reliable and valid instrument evaluated by the current study. [source] Does patient feedback improve the consultation skills of general practice trainees?MEDICAL EDUCATION, Issue 2 2010A controlled trial Medical Education 2010:44: 156,164 Context, This study aimed to assess if an additional patient feedback training programme leads to better consultation skills in general practice trainees (GPTs) than regular communication skills training, and whether process measurements (intensity of participation in the programme) predict the effect of the intervention. Methods, We carried out a controlled trial in which two sub-cohorts of GPTs were allocated to an intervention group (n = 23) or a control group (n = 30), respectively. In 2006, allocated first-year GPTs in the VU University Medical Centre attended a patient feedback training programme in addition to the regular communication skills training. The control group attended only regular communication skills training. Trainees were assessed by simulated patients who visited the practices and videotaped the consultations at baseline and after 3 months. The videotapes were randomly assigned to eight trained staff members. The MAAS-Global Instrument (range 0,6) was used to assess (a change in) trainee consultation skills. Results were analysed using a multi-level, linear mixed-model analysis. Results, Data on 50 GPTs were available for the follow-up analysis. Both intervention group and control group GPTs improved their consultation skills: mean MAAS-Global scores for all participants were 3.29 (standard deviation [SD] 0.75) at baseline and 3.54 (SD 0.66) at follow-up (P = 0.047). The improvement in MAAS-Global scores in the intervention group did not differ significantly from the improvement in the control group. The analysis showed a trend for intensity of participation in the patient feedback programme to predict greater improvement in MAAS-Global scores. Discussion, Although the baseline scores were already in the high range, consultation skills in both groups improved significantly. This is reassuring for current teaching methods. The patient feedback programme did not improve consultation skills more than regular communication skills training. However, a subgroup of GPTs who participated intensively in the programme did improve their consultation skills further in comparison with the less motivated subgroup. [source] Using scanning electron, confocal and optical microscopes to measure microscopic holes in traysPACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2005Laura Bix Abstract Package integrity is of paramount importance to the medical device industry. As healthcare costs soar and integrity testers become more and more sensitive, concern with the question ,what hole size allows microbial penetration into device packages?' is re-ignited. However, producing a consistent and measurable defect in the microcosm presents challenges. Varying techniques are currently employed to produce these defects. Use of an excimer laser is one of the most precise and accurate techniques, and holes ,certified' to be a given size can be purchased at a significant cost. To verify the accuracy and precision of holes drilled with an excimer laser, researchers measured laser-drilled ,exit' and ,entry' holes in glycol-modified polyetheylene terephthalate (PETG) trays using scanning electron microscopy (SEM) and confocal microscopy. This data and the certification data provided by the laser driller were analysed using a mixed-model analysis of variance (ANOVA). Both the effect of measuring technique and hole side (entry vs. exit) were found to be significant. These significant differences have the potential to impact the question that the industry faces with regard to penetration threshold. This suggests that a shift in thinking is needed. Perhaps it would be better if the industry stops thinking about hole size and begins to think in terms of what researchers have referred to as the ,effective hole', which is defined as the volume of gas that will flow through a hole of defined size per unit time. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||