Functional data analysis (FDA) -the analysis of data that can be considered a set of observed continuous functions -is an increasingly common class of statistical analysis. One of the most widely used FDA methods is the cluster analysis of functional data; however, little work has been done to compare the performance of clustering methods on functional data. In this paper a simulation study compares the performance of four major hierarchical methods for clustering functional data. The simulated data varied in three ways: the nature of the signal functions (periodic, non-periodic, or mixed), the amount of noise added to the signal functions, and the pattern of the true cluster sizes. The Rand index was used to compare the performance of each clustering method. As a secondary goal, clustering methods were also compared when the number of clusters has been misspecified. To illustrate the results, a real set of functional data was clustered where the true clustering structure is believed to be known. Comparing the clustering methods for the real data set confirmed the findings of the simulation. This study yields concrete suggestions to future researchers to determine the best method for clustering their functional data.

Scope-Diabetic embryopathy, a consequence of diabetic pregnancy is associated with increase in embryonic oxidative stress and apoptosis which lead to severe embryonic damage at early stage of organogenesis.Methods and results-This study investigated if resveratrol, found in red grapes and blueberries, may prevent diabetes-induced oxidative stress and apoptosis in embryos and have beneficial effects in diabetic dams. A rodent model of diabetic embryopathy was used. Diabetes was associated with lowered reduced glutathione levels (26.98%), increased total thiol (100.47%) and lipid peroxidation (124.73%) in embryos, and increased blood sugar (384.03%), cholesterol (98.39%) and triglyceride (1025.35%) in diabetic dams. Increased apoptosis (272.20%) was also observed in the embryos of diabetic dams. Administration of resveratrol (100 mg/kg b. wt.) during pregnancy prevented both oxidative stress and apoptosis in embryos. Resveratrol reduced embryonic maldevelopment by improving embryo weight (41.23%), crown rump length (16.50%) and somite number (11.22%). It further improved the glucose (33.32%) and lipid (cholesterol 41.74%, triglyceride 60.64%) profile of the diabetic dams which also represents the protective role of resveratrol in diabetes.Conclusion-Resveratrol was found to prevent embryonic oxidative stress and apoptosis. It also improved glucose and lipid profile of diabetic dams indicating the beneficial effects in diabetic pregnancy.

This article surveys Bayesian methods for categorical data analysis, with primary emphasis on contingency table analysis. Early innovations were proposed by Good (1953Good ( , 1956Good ( , 1965 for smoothing proportions in contingency tables and by Lindley (1964) for inference about odds ratios. These approaches primarily used conjugate beta and Dirichlet priors. Altham (1969Altham ( , 1971 presented Bayesian analogs of small-sample frequentist tests for 2×2 tables using such priors. An alternative approach using normal priors for logits received considerable attention in the 1970s by Leonard and others (e.g., Leonard 1972). Adopted usually in a hierarchical form, the logit-normal approach allows greater flexibility and scope for generalization. The 1970s also saw considerable interest in loglinear modeling. The advent of modern computational methods since the mid-1980s has led to a growing literature on fully Bayesian analyses with models for categorical data, with main emphasis on generalized linear models such as logistic regression for binary and multi-category response variables.

Background Practitioners and researchers are interested in assessing children’s dietary intake and physical activity together to maximize resources and minimize subject burden. Objective To investigate differences in dietary and/or physical-activity recall accuracy by content (diet-only; physical-activity-only; diet-&-physical-activity), retention interval (same-day-recalls-in-the-afternoon; previous-day-recalls-in-the-morning), and grade (third; fifth). Design Children (n=144; 66% African American, 13% White, 12% Hispanic, 9% Other; 50% girls) from four schools were randomly selected for interviews about one of three contents. Each content group was equally divided by retention interval, each equally divided by grade, each equally divided by sex. Information concerning diet and physical activity at school was validated with school-provided breakfast and lunch observations, and accelerometry, respectively. Dietary accuracy measures were food-item omission and intrusion rates, and kilocalorie correspondence rate and inflation ratio. Physical activity accuracy measures were absolute and arithmetic differences for moderate-to-vigorous-physical-activity minutes. Statistical analyses performed For each accuracy measure, linear models determined effects of content, retention interval, grade, and their two-way and three-way interactions; ethnicity and sex were control variables. Results Content was significant within four interactions: intrusion rate (content-×-retention-interval-×-grade; p=.0004), correspondence rate (content-×-grade; p=.0004), inflation ratio (content-×-grade; p=.0104), and arithmetic difference (content-×-retention-interval-×-grade; p=.0070). Retention interval was significant for correspondence rate (p=.0004), inflation ratio (p=.0014), and three interactions: omission rate (retention-interval-×-grade; p=.0095), intrusion rate, and arithmetic difference (both already mentioned). Grade was significant for absolute difference (p=.0233) and five interactions mentioned. Content effects depended on other factors. Grade effects were mixed. Dietary accuracy was better with same-day than previous-day retention interval. Conclusions Results do not support integrating dietary intake and physical activity in children’s recalls, but do support using shorter rather than longer retention intervals to yield more accurate dietary recalls. Further validation studies need to clarify age effects and identify evidence-based practices to improve children’s accuracy for recalling dietary intake and/or physical activity.

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