Using simulation methods, we estimated the power requirements for

Using simulation methods, we estimated the power requirements for interrupted time series studies under various scenarios.

Study Design and Setting: Simulations were conducted to estimate the power of segmented autoregressive (AR) error models when autocorrelation ranged

from -0.9 to 0.9 and effect size was 0.5, 1.0, and 2.0, investigating balanced and unbalanced numbers of time periods before and after an intervention. Simple scenarios of autoregressive conditional heteroskedasticity (ARCH) models were also explored.

Results: For AR models, power increased when sample size or effect size increased, and tended to decrease when autocorrelation increased. Compared with a balanced number of study periods before and after an intervention,

SB202190 nmr designs with unbalanced numbers of periods had less power, although that was not the case for ARCH models.

Conclusion: The power to detect effect size 1.0 appeared to be reasonable for many practical applications with a moderate or large number of time points in the study equally divided around the intervention. Investigators should be cautious when the expected effect size is small or the number check details of time points is small. We recommend conducting various simulations before investigation. (C) 2011 Elsevier Inc. All rights reserved.”
“The aim of this paper was to systematically review the evidence for the association between television viewing and diet in children ages 26. Data sources included PubMed, PsycINFO, EMBASE, ERIC, SportDISCUS, Sociological Abstracts, Web of Science and hand searches of reference lists of relevant articles. Twelve studies were reviewed in which the relationship between television viewing and diet was assessed in children between the ages of 2 and 6. All but one study reported significant relationship between television viewing time and adverse dietary outcomes. Parent-reported television viewing time was used to assay child television viewing in all included studies. Food frequency survey was the most frequent method of dietary assessment, and parent served as proxies for children in all studies. Lower fruit

and/or vegetable intake was the most frequently reported dietary outcome, followed by increased energy intake with increased television viewing. The majority of studies reported adverse dietary outcomes with as little selleck compound as 1 h of daily television exposure. While these results are consistent with recommendations from child health advocates to limit television viewing in young children, they also suggest that further efforts to limit television viewing in young children may be needed to aid in obesity prevention.”
“Cost-sharing for health care is high on the policy agenda in many European countries that struggle with deficits in their public budget. However, such policy often meets with public opposition, which might delay or even prevent its implementation.

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