Dietary diversity scores can be improved through the use of portion requirements: an analysis in young Filipino children.

OBJECTIVES: Early childhood malnutrition is a pressing international concern which dietary diversity scores (summary scores of food groups in the diet) may be helpful in addressing. We explored three current research needs surrounding diversity scores: the impact of portion size on score function, the relationship of scores to nutrient adequacy and density and the ability of scores to function as screening tools. SUBJECTS/METHODS: 1810 children, age 24 months. Cross sectional study of a birth cohort. RESULTS: We evaluated two nine food group dietary diversity scores based on 0 and 10 g minimum food group requirements for their relationship to nutrient adequacy and nutrient density. Both scores were significantly correlated with nutrient adequacy and density and predicted statistically significant increases (P<0.05) in the probability of adequacy for all nutrients. However, correlations and predicted increases were somewhat larger for the 10 g score. We also considered the sensitivity and specificity of each score for detecting low and high nutrient adequacy in the population. The 10 g cutoff improved score ability to predict low nutrient adequacy, and reduced the misclassification of subjects for all comparisons. CONCLUSIONS: This research suggests that the score without portion requirements reflects dietary adequacy, but when feasible, further refinement of diversity scores is desirable through the application of minimum portion requirements.

Nonparametric regression estimates with censored data: local linear smoothers and their applications.

For censored time-to-event data, Beran (unpublished manuscript), followed by Doksum and Yandell (1982, Properties of Regression Estimates Based on Censored Survival Data) and Dabrowska (1987, Scandinavian Journal of Statistics 14, 181-197), suggested a nonparametric regression technique based on the kernel method to estimate the conditional survival function. We propose to improve the bias term and boundary effects of their procedure by using local linear fits. This is illustrated in this paper with simulated and real data. Moreover, consistency results for the local linear-based estimates of the conditional survival, cumulative hazard, mean, and median functions are also established.

A general statistical framework for frequency-domain analysis of EEG topographic structure.

A wide variety of rhythmic electrophysiological phenomena--including driven, induced, and endogenous activities of cortical neuronal masses--lend themselves naturally to analysis using frequency--domain techniques applied to multichannel recordings that discretely sample the overall spatial pattern of the rhythmic activity. For such cases, a large but so far poorly utilized body of statistical theory supports a third major approach to topographic analysis, complementing the more familiar mapping and source-recovery techniques. These methods, many of which have only recently become computationally feasible, collectively provide general solutions to the problem of detecting and characterizing systematic differences that arise--not only in the spatial distribution of the activity, but also in its frequency-dependent between-channel covariance structure--as a function of multiple experimental conditions presented in conformity with any of the conventional experimental designs. This application-oriented tutorial review provides a comprehensive outline of these resources, including: (1) real multivariate analysis of single-channel spectral measures (and measures of between-channel relationships such as coherence and phase), (2) complex multivariate analysis based on multichannel Fourier transforms, and (3) complex multivariate analysis based on multichannel parametric models. Special emphasis is placed on the potential of the multichannel autoregressive model to support EEG (and MEG) studies of perceptual and cognitive processes.

Cotinine concentrations in semen, urine, and blood of smokers and nonsmokers.

Cotinine levels in the semen, urine, and blood of 88 male smokers and nonsmokers, aged 18 to 35, were analyzed via radioimmunoassay. Detectable cotinine levels were found in all three body fluids, and cotinine levels in all three fluids were highly correlated. Cotinine levels in semen and blood were of similar magnitude; cotinine levels in urine were an order of magnitude or more higher. In all three fluids, cotinine levels increased with an increase in cigarette smoke exposure.