The effect of xylanase, phytase and lipase supplementation on the performance of broiler chickens fed a diet with a high level of rice bran.

Enzyme products did not have a significant effect (P>0.05) on weekly fed intake and weight gain of birds. But feed intake tended to drop and weight gain tended to increase in response to supplementation of the three enzymes. Weight gain of the birds was increased by 0.6% with lipase, 3.7% with phytase and 2.4% with xylanase. Xylanase had a marked effect (P

On the use of likert-type scales in multilevel data:Influence on aggregate variables

In multilevel analyses, problems may arise when using Likert-type scales at the lowest level of analysis. Specifically, increases in variance should lead to greater censoring for the groups whose true scores fall at either end of the distribution. The current study used simulation methods to examine the influence of single-item Likert-type scale usage on ICC(1), ICC(2), and group-level correlations. Results revealed substantial underestimation of ICC(1) when using Likert-type scales with common response formats (e.g., 5 points). ICC(2) and group-level correlations were also underestimated, but to a lesser extent. Finally, the magnitude of underestimation was driven in large part to an interaction between Likert-type scale usage and the amounts of within- and between-group variance. © Sage Publications.

Job satisfaction and teamwork:The role of supervisor support

The link between teamwork and job satisfaction was investigated in a sample of 48 manufacturing companies comprising 4708 employees. Two separate research questions were addressed. First, it was proposed that supervisor support would be a weaker source of job satisfaction in companies with higher levels of teamworking. Multilevel analysis indicated that the extent of teamwork at the company level of analysis moderated the relationship between individual perceptions of supervisor support and job satisfaction. Second, it was proposed that the extent of teamwork would be positively related to perceptions of job autonomy but negatively related to perceptions of supervisor support. Further, it was proposed that the link between teamwork and job autonomy would be explained by job enrichment practices associated with teamwork. Analyses of aggregated company data supported these propositions and provided evidence for a complex mediational path between teamwork and job satisfaction. Implications for implementing teamwork in organizations are discussed. Copyright © 2001 John Wiley & Sons, Ltd.

The application of analysis of variance (ANOVA) to different experimental designs in optometry

Analysis of variance (ANOVA) is the most efficient method available for the analysis of experimental data. Analysis of variance is a method of considerable complexity and subtlety, with many different variations, each of which applies in a particular experimental context. Hence, it is possible to apply the wrong type of ANOVA to data and, therefore, to draw an erroneous conclusion from an experiment. This article reviews the types of ANOVA most likely to arise in clinical experiments in optometry including the one-way ANOVA ('fixed' and 'random effect' models), two-way ANOVA in randomised blocks, three-way ANOVA, and factorial experimental designs (including the varieties known as 'split-plot' and 'repeated measures'). For each ANOVA, the appropriate experimental design is described, a statistical model is formulated, and the advantages and limitations of each type of design discussed. In addition, the problems of non-conformity to the statistical model and determination of the number of replications are considered. © 2002 The College of Optometrists.

Anger and perceived legitimacy of aggression in male Hong Kong Chinese athletes: Effects of type of sport and level of competition

Problem: The vast majority of research examining the interplay between aggressive emotions, beliefs, behaviors, cognitions, and situational contingencies in competitive athletes has focused on Western populations and only select sports (e.g., ice hockey). Research involving Eastern, particularly Chinese, athletes is surprisingly sparse given the sheer size of these populations. Thus, this study examines the aggressive emotions, beliefs, behaviors, and cognitions, of competitive Chinese athletes. Method: Several measures related to aggression were distributed to a large sample (N ¼ 471) of male athletes, representing four sports (basketball, rugby union, association football/soccer, and squash). Results: Higher levels of anger and aggression tended to be associated with higher levels of play for rugby and low levels of play for contact (e.g., football, basketball) and individual sports (e.g., squash). Conclusions: The results suggest that the experience of angry emotions and aggressive behaviors of Chinese athletes are similar to Western populations, but that sport psychology practitioners should be aware of some potentially important differences, such as the general tendency of Chinese athletes to disapprove of aggressive behavior.

The use of analysis of variance (ANOVA) in applied microbiology

Experiments combining different groups or factors and which use ANOVA are a powerful method of investigation in applied microbiology. ANOVA enables not only the effect of individual factors to be estimated but also their interactions; information which cannot be obtained readily when factors are investigated separately. In addition, combining different treatments or factors in a single experiment is more efficient and often reduces the number of replications required to estimate treatment effects adequately. Because of the treatment combinations used in a factorial experiment, the DF of the error term in the ANOVA is a more important indicator of the ‘power’ of the experiment than the number of replicates. A good method is to ensure, where possible, that sufficient replication is present to achieve 15 DF for each error term of the ANOVA. Finally, it is important to consider the design of the experiment because this determines the appropriate ANOVA to use. Some of the most common experimental designs used in the biosciences and their relevant ANOVAs are discussed by. If there is doubt about which ANOVA to use, the researcher should seek advice from a statistician with experience of research in applied microbiology.