The log transformation is special

Keene, Oliver N.

doi:10.1002/sim.4780140810

Cited by 423 publications

(288 citation statements)

References 13 publications

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“…Because all PA variables were positively skewed, logarithmic transformations (log10) were used to improve normality. 37 For step counts, average values of more than 20,000 steps/day were recorded as 20,000 to limit unrealistically high averages. 33 Because prior chi-square tests and independent sample t tests showed that the urban and rural samples were comparable on all sociodemographic characteristics except for educational level (pG 0.001) and working situation (pG0.01), three-way interactions between the physical environment (urban versus rural), psychosocial factors (modeling from family and friends, social support from family and friends, self-efficacy, perceived benefits ([five factors] and perceived barriers [five factors]), and SES (low versus high education) in relation to PA were investigated using ANOVA models.…”

Section: Resultsmentioning

confidence: 99%

Urban–Rural Differences in Physical Activity in Belgian Adults and the Importance of Psychosocial Factors

et al. 2011

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Recent research in urban planning and public health has drawn attention to the associations between urban form and physical activity in adults. Because little is known on the urban-rural differences in physical activity, the main aims of the present study were to examine differences in physical activity between urban and rural adults and to investigate the moderating effects of the physical environment on the relationship between psychosocial factors and physical activity. In Flanders, Belgium, five rural and five urban neighborhoods were selected. A sample of 350 adults (20-65 years of age; 35 adults per neighborhood) participated in the study. Participants wore a pedometer for 7 days, and self-reported physical activity and psychosocial data were also collected. Results showed that urban adults took more steps/day and reported more walking and cycling for transport in the neighborhood, more recreational walking in the neighborhood, and more walking for transportation outside the neighborhood than rural adults. Rural adults reported more recreational cycling in the neighborhoods. The physical environment was a significant moderator of the associations between several psychosocial factors (modeling from family, self-efficacy, and perceived barriers) and physical activity. In rural participants, adults with psychosocial scores above average were more physically active, whereas there were no differences in physical activity according to psychosocial factors in urban participants. These results are promising and plead for the development of multidimensional interventions, targeting specific population subgroups. In rural environments, where changing the environment would be a very challenging task, interventions focusing on modifiable psychosocial constructs could possibly be effective.

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Section: Resultsmentioning

confidence: 99%

Urban–Rural Differences in Physical Activity in Belgian Adults and the Importance of Psychosocial Factors

et al. 2011

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“…Natural logarithmic transformation of all biomarkers and dietary data were performed to reduce the within-sample variability and to avoid inappropriate exclusion of outliers. (59) Therefore, the size of the regression coefficient represents the proportional change in BAP or uNTx/Cr associated with a unit change in the predictor variable. Adjusting for total serum cholesterol instead of serum triglycerides gave similar results to the unadjusted analysis; therefore, only serum triglyceride was used.…”

Section: Discussionmentioning

confidence: 99%

Effects of vitamin E on bone turnover markers among US postmenopausal women

Hamidi

Corey

Cheung

2012

Journal of Bone and Mineral Research

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Increased oxidative stress and inflammation resulting from aging and declining estrogen levels can lead to increased bone loss in postmenopausal women. Alpha-tocopherol and gamma-tocopherol, the two predominant isomers of vitamin E, have antioxidant and anti-inflammatory properties, but their effects on bone metabolism have not been well studied in humans. We examined the associations between dietary and total (diet and supplements) alpha-tocopherol intake, serum alpha-tocopherol and gamma-tocopherol levels and their ratio, and bone turnover markers (BTMs) among postmenopausal women aged !45 years. We used cross-sectional data from the National Health and Nutrition Examination Survey 1999-2002. Multiple regression models with adjustments for relevant confounders were used to examine the associations between intake and serum levels of tocopherols, and serum bone-specific alkaline phosphatase (BAP), a biomarker of bone formation, and urinary N-telopeptides/creatinine (uNTx/Cr), a biomarker of bone resorption. The study sample included 497 postmenopausal women who were not taking estrogen, steroids, or osteoporosis medications, were free from kidney and liver disease, cancer, and rheumatoid arthritis, and were fasting >9 hours prior to examination. Participants had a mean age of 65.5 AE 0.6 years and over 45% used vitamin E (alpha-tocopherol) supplements in the past month. Vitamin E supplement users had significantly lower serum gamma-tocopherol, higher serum alpha-tocopherol levels, and higher ratio of serum alpha-tocopherol to gamma-tocopherol than nonusers. High serum gamma-tocopherol levels and low ratio of serum alpha-tocopherol to gamma-tocopherol were associated with increased BAP levels (p < 0.01 for both). There were no associations between any of the vitamin E variables and uNTx/Cr. In conclusion, we hypothesize that gamma-tocopherol may uncouple bone turnover, resulting in more bone formation than resorption. Vitamin E supplements in the form of alpha-tocopherol suppress serum gamma-tocopherol levels and may have negative effects on bone formation. Further research is needed to investigate the potential anabolic effect of gamma-tocopherol from food sources on bone. ß

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“…Dissociation of phasic and sustained fear L Miles et al (K2 ¼ 51.78) and phasic fear (K2 ¼ 45.53) data sets, and because Grubb's test identified several outliers, betweengroup differences were evaluated using distribution-free (non-parametric) Mann-Whitney or Kruskal-Wallis tests, and also, to establish statistical robustness, by using t-tests and ANOVA on log-transformed scores (see Keene (1995)). Follow-up comparisons were made using Dunn's (nonparametric) or Dunnett's t-test (parametric) for multiple comparisons with a control.…”

Section: Statistical Analysesmentioning

confidence: 99%

Phasic and Sustained Fear are Pharmacologically Dissociable in Rats

Miles

Davis

Walker

2011

Neuropsychopharmacol

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Previous findings suggest differences in the neuroanatomical substrates of short-(seconds) vs longer-duration (minutes) fear responses. We now report that phasic and sustained fear can also be differentiated pharmacologically, based on their response to several treatments that either are or are not clinically effective anxiolytics. For these experiments, short-or long-duration clicker stimuli were paired with footshock. Acoustic startle amplitude was later measured in the absence of the clicker, or within seconds (phasic fear) or minutes (sustained fear) of its onset. Before testing, rats received a single injection of vehicle, the benzodiazepine chlordiazepoxide, the 5HT 1A agonist and dopamine D2 antagonist buspirone, the selective serotonin reuptake inhibitor fluoxetine, or a 3-week treatment with either vehicle or fluoxetine. Chlordiazepoxide blocked sustained, but not phasic startle increases. Acute buspirone, which is not anxiolytic in human beings, did not affect sustained startle increases, but did disrupt phasic increases. Chronic fluoxetine blocked sustained startle increases and unreliably reduced phasic increases; acute fluoxetine affected neither. The results indicate that phasic and sustained fear responses can be pharmacologically dissociated, further validating this distinction, and suggest that sustained startle increases may be especially useful as anxiety models and anxiolytic screens.

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The log transformation is special

Cited by 423 publications

References 13 publications

Urban–Rural Differences in Physical Activity in Belgian Adults and the Importance of Psychosocial Factors

Urban–Rural Differences in Physical Activity in Belgian Adults and the Importance of Psychosocial Factors

Effects of vitamin E on bone turnover markers among US postmenopausal women

Phasic and Sustained Fear are Pharmacologically Dissociable in Rats

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