Dataset Information

Day length may make geographical difference in body size and proportions: An ecological analysis of Japanese children and adolescents.

ABSTRACT: There is a north-south gradient in the body heights of Japanese children. A hypothesis had previously been proposed that differences in thyroid hormone activity induced by geographical differences in effective day length (duration of photoperiod exceeding a predetermined light intensity) might cause the differences in height. If thyroid hormone is involved, the effect should extend to body weight. This study examined whether geographical differences in body height and weight can be explained in terms of thyroid hormone activity induced by geographical differences in the photoperiodic environment using prefecture-level anatomical data and Japanese Mesh Climatic Data. Multiple regression analysis demonstrated that the combination of effective day length and weight was statistically significant as a predictor of height. Controlling for body weight revealed that effective day length was inversely correlated with height. Multiple regression analysis revealed that a combination of effective day length and height was statistically significant as a predictor of weight. Controlling for height demonstrated that effective day length was positively correlated with weight. Assuming an inverse correlation between effective day length and thyroid hormone activity, these results appear to show that short day-length will increase the activity of thyroid hormone and contribute to increasing height, but will inhibit weight gain; in contrast, long day-length will decrease the activity of thyroid hormone and contribute to increasing weight but will inhibit height gain. Geographical differences in height, and weight, and part of the prevalence of obesity in Japanese children and early adolescents may be explained by geographical differences in effective day length.

SUBMITTER: Yokoya M

PROVIDER: S-EPMC6342304 | biostudies-other | 2019

REPOSITORIES: biostudies-other

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Day length may make geographical difference in body size and proportions: An ecological analysis of Japanese children and adolescents.

Yokoya Masana M Higuchi Yukito Y

PloS one 20190122 1

There is a north-south gradient in the body heights of Japanese children. A hypothesis had previously been proposed that differences in thyroid hormone activity induced by geographical differences in effective day length (duration of photoperiod exceeding a predetermined light intensity) might cause the differences in height. If thyroid hormone is involved, the effect should extend to body weight. This study examined whether geographical differences in body height and weight can be explained in ...[more]

PMID: 30668608

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Project description:General Practitioners (GPs) respond poorly to postal surveys. Consequently there is potential for reduced data quality and bias in the findings. In general population surveys, response to postal questionnaires may be improved by reducing their length and offering incentives. The aim of this study was to investigate whether questionnaire length and/or the offer of an incentive improves the response of GPs to a postal questionnaire survey.A postal questionnaire survey was sent to 800 UK GPs randomly selected from Binley's database; a database containing contact details of professionals working in UK general practices. The random sample of GPs was assigned to one of four groups of 200, each receiving a different questionnaire, either a standard (eight sides of A4) or an abbreviated (four sides of A4) questionnaire, with or without the offer of an incentive (a prize draw entry for a £100 voucher) for completion. The effects of questionnaire length and offer of incentive on response were calculated.Of 800 mailed questionnaires, 19 GPs did not meet inclusion criteria and 172 (adjusted response 22.0%) completed questionnaires were received. Among the four groups, response ranged from 20.1% (standard questionnaire with no incentive and abbreviated questionnaire with incentive) through 21.8% (standard questionnaire with incentive), to 26.0% (abbreviated questionnaire with no incentive). There were no significant differences in response between the four groups (p?=?0.447), between the groups receiving the standard versus the abbreviated questionnaire (% difference -2.1% (95% confidence interval (CI) -7.9, 3.7)) or the groups offered an incentive versus no incentive (% difference -2.1% (95% CI -7.9, 3.7).Strategies known to improve response to postal questionnaire surveys in the general population do not significantly improve the response to postal questionnaire surveys among GPs. Further refinements to these strategies, or more novel strategies, aimed at increasing response specifically among GPs need to be identified in order to maximise data quality and generalisability of research results.

Dataset Information

Day length may make geographical difference in body size and proportions: An ecological analysis of Japanese children and adolescents.

Publications

Day length may make geographical difference in body size and proportions: An ecological analysis of Japanese children and adolescents.

Similar Datasets

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