Lois M. Collins

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This article illustrates the use of latent transition analysis (LTA), a methodology for testing stage-sequential models of individual growth. LTA is an outgrowth of latent class theory and is a particular type of latent Markov model emphasizing the use of multiple manifest indicators. LTA is used to compare the fit of two models of early adolescent(More)
Latent class models with sparse contingency tables can present problems for model comparison and selection, because under these conditions the distributions of goodness-of-fit indices are often unknown. This causes inaccuracies both in hypothesis testing and in model comparisons based on normed indices. In order to assess the extent of this problem, we(More)
Cudeck and Browne (1983) were among the first to discuss the advantages of taking a crossvalidation approach to testing of covariance structure models. The purpose of this paper is to expand on Cudeck and Browne's work in two directions. The first direction of expansion is into testing of latent class models. The second direction of expansion involves using(More)
Contrary to a commonly held belief that broiler chickens need more space, there is increasing evidence that these birds are attracted to other birds. Indeed, commercially farmed birds exhibit a range of socially facilitated behaviours, such as increased feeding and preening in response to the presence of other birds. Social facilitation can generate(More)
Many readers of this monograph may wonder why a chapter on statistical power was included. After all, by now the issue of statistical power is in many respects mundane. Everyone knows that statistical power is a central research consideration, and certainly most National Institute on Drug Abuse grantees or prospective grantees understand the importance of(More)
have that luxury in commercial fl ocks, and in extreme situations, this leads to unintentional feed restriction. It is very unusual for young broilers to be intentionally feed restricted, although very short day lengths — a practice that was common 10 years ago to combat ascites — had this intentional effect. Likewise, limiting feed intake of birds as early(More)
of the Department of Statistics were participants on the KBYU program " Thinking Aloud " which aired on 26 October, 2006. The program focused on the growing use of data in everyday life. One concerned voiced by the radio host was whether or not individuals could be biased or unfairly influenced by unscrupulous use of data. Both Drs. Reese and Tolley brought(More)
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