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Results for “Effect Modifier, Epidemiologic”

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PubMed2003

How stable is the risk curve between alcohol and all-cause mortality and what factors influence the shape? A precision-weighted hierarchical meta-analysis.

OBJECTIVE: To determine the influence of six determining variables on the shape of the risk curve between alcohol and all-cause mortality. METHODS DATA: Based on a systematic search with clear inclusion criteria, all articles on alcohol and all-cause mortality until 2000 were included. STATISTICAL METHODS: Precision-weighted pooling of relative risks (RRs); precision-weighted hierarchical analysis. VARIABLES: For pooling: RRs for different categories of average volume of drinking, lifetime abstainers and ex-drinkers. For hierarchical analysis: on first level: consumption in grams of pure alcohol per day; on second level: length of follow-up time in months; per capita consumption; average age, proportion of abstainers, average volume of drinking, and variability of average volume of drinking at baseline. OUTCOMES MEASURES: RR of former and current drinkers for all-cause mortality compared to abstainers. RESULTS: The main hypotheses could be confirmed for males: Ex-drinkers had a higher mortality risk than lifetime abstainers; the higher and the more diverse the average volume of alcohol consumption, the wider the dip of the curve; the older the persons at baseline, the more pronounced the protective effect; and the longer the follow-up time, the less pronounced the protective effect. Except for average volume of drinking effects for females went in the same direction but with one exception did not reach significance. CONCLUSIONS: There are systematic influences on the shape of the risk curve between alcohol and all-cause mortality. The overall beneficial effect of light to moderate drinking remained under all scenarios, indicating a high validity of the overall shape despite the heterogeneity between studies.

Age Distribution↗
PubMed2004

The effective use of a summary table and decision tree methodology to analyze very large healthcare datasets.

Very large datasets typically consists of millions of records, with many variables. Such datasets are stored and maintained by organizations because of the perceived potential information they contain. However, the problem with very large datasets is that traditional methods of data mining are not capable of retrieving this information because the software may be overwhelmed by the memory or computing requirements. In this article we outline a method that can analyze very large datasets. The method initially performs a data reduction step through the use of a summary table, which is then used as a reference dataset that is recursively partitioned to grow a decision tree.

Data Interpretation, Statistical↗
PubMed2005

[Emotional and behavioral disorders at preschool age--results of a study in kindergarten children in Dortmund using the Caregiver-Teacher Report Form C-TRF/1 1/2-5].

OBJECTIVES: Currently there is a lack of screening instruments suitable for use by preschool and kindergarten teaches to assess behavioural and emotional problems in preschool children. The C-TRF/1 1/2-5 (Caregiver-Teacher Report Form for the ages 1 1/2-5) is a screening instrument designed by Achenbach to assess behavioural and emotional problems in this age group. In a joint project of the Fachhochschule Dortmund and the Department of Child and Adolescent Psychiatry, University of Ulm, in cooperation with the Youth Welfare Office Dortmund, the C-TRF/1 1/2-5 was used to assess the prevalence of psychological disturbance among kindergarten children. METHODS: 1,050 children aged 3-6 years from 46 kindergartens from the greater Dortmund urban area were rated by their caregivers on the basis of the German version of the C-TRF/1 1/2-5. RESULTS: The reliability of C-TRF/1 1/2-5 proved to be good-to-sufficient, with internal consistencies ranging from .94 to .58. The number of behavioural and emotional problems, which is very close to that found among American preschool children, decreases with age and more strongly so among girls. The externalizing problems among boys do not decrease much, but remain quite stable from age 3 to age 6. The prevalence of internalizing problems among preschool boys and girls does not differ. CONCLUSIONS: The German version of the C-TRF/1 1/2-5 proved to be an instrument sufficiently reliable for screening behavioural and emotional problems in preschool children. The prevalence of these psychological problems among German and American children is very similar.

Affective Symptoms↗
PubMed1998

Strategies for analyzing ecological momentary assessment data.

Studies incorporating repeated observations of momentary phenomena are becoming more common in behavioral and medical science. Analysis of such data requires the use of statistical techniques that are unfamiliar to many investigators. Some common ways of analyzing momentary data are reviewed--aggregation strategies, repeated measures analysis of variance, pooled within-person regression, and two-stage estimation procedures for multilevel models--and are found to be usually suboptimal, possibly leading to incorrect inferences. A broad class of statistical models for multilevel data that can address many research questions typically asked of momentary data are then described. Analytic issues that merit careful consideration include the scaling of momentary variables, allowance for serial autocorrelation of residuals, and the treatment of coefficients that vary across individuals as fixed versus random effects.

Analysis of Variance↗
PubMed2000

Understanding the latent structure of job performance ratings.

This study quantified the effects of 5 factors postulated to influence performance ratings: the ratee's general level of performance, the ratee's performance on a specific dimension, the rater's idiosyncratic rating tendencies, the rater's organizational perspective, and random measurement error. Two large data sets, consisting of managers (n = 2,350 and n = 2,142) who received developmental ratings on 3 performance dimensions from 7 raters (2 bosses, 2 peers, 2 subordinates, and self) were used. Results indicated that idiosyncratic rater effects (62% and 53%) accounted for over half of the rating variance in both data sets. The combined effects of general and dimensional ratee performance (21% and 25%) were less than half the size of the idiosyncratic rater effects. Small perspective-related effects were found in boss and subordinate ratings but not in peer ratings. Average random error effects in the 2 data sets were 11% and 18%.

Bias↗
PubMed2002

Race and self-esteem: meta-analyses comparing whites, blacks, Hispanics, Asians, and American Indians and comment on Gray-Little and Hafdahl (2000).

These meta-analyses examine race differences in self-esteem among 712 datapoints. Blacks scored higher than Whites on self-esteem measures (d = 0.19), but Whites scored higher than other racial minority groups, including Hispanics (d = -0.09), Asians (d = -0.30), and American Indians (d = -0.21). Most of these differences were smallest in childhood and grew larger with age. Blacks' self-esteem increased over time relative to Whites', with the Black advantage not appearing until the 1980s. Black and Hispanic samples scored higher on measures without an academic self-esteem subscale. Relative to Whites, minority males had lower self-esteem than did minority females, and Black and Hispanic self-esteem was higher in groups with high socioeconomic status. The results are most consistent with a cultural interpretation of racial differences in self-esteem.

Adolescent↗
PubMed2004

A missing link in suggestibility research: what is known about the behavior of field interviewers in unstructured interviews with young children?

Despite suggestibility researchers' focus on adult behaviors that distort children's reports, whether behaviors examined in experimental work are used in the field is unknown. The current study presents a mutually exclusive and exhaustive hierarchical coding system that reflects interview questioning behaviors of concern in experimental work. The study examined 80 unstructured interviews conducted by 41 field interviewers with 40 children ages 3 to 7 about known events. Data on the use of leading and neutral questions are presented and include distinctions between accurate and inaccurate suggested information. In addition, analyses show that interviewers are consistent in their style of questioning and that a preinterview measure of interviewers' preference for a qualitative versus a quantitative interviewing style predicted the introduction of novel information into the interview.

Child↗
PubMed2005

Work stress, substance use, and depression among young adult workers: an examination of main and moderator effect model.

In this cross-sectional study, main and moderated relationships between 5 job stressors and alcohol consumption, drug use, and depression were examined using data from a community sample of 583 young adults (mean age = 23.68 years). Analyses revealed a few direct associations between high job boredom, low skill variety, and low autonomy and depression measures and heavy alcohol use. There were no direct relationships between job stress and binge drinking, alcohol consumption, drug use, or heavy drug use. In a few cases, job stress-outcome relationships were moderated by intrinsic job motivation or gender. The findings supported a specificity-of-effects hypothesis and underscored the need for examining the processes linking occupational stress to substance use and depression.

Adult↗
PubMed2005

An alternative to Cohen's standardized mean difference effect size: a robust parameter and confidence interval in the two independent groups case.

The authors argue that a robust version of Cohen's effect size constructed by replacing population means with 20% trimmed means and the population standard deviation with the square root of a 20% Winsorized variance is a better measure of population separation than is Cohen's effect size. The authors investigated coverage probability for confidence intervals for the new effect size measure. The confidence intervals were constructed by using the noncentral t distribution and the percentile bootstrap. Over the range of distributions and effect sizes investigated in the study, coverage probability was better for the percentile bootstrap confidence interval.

Analysis of Variance↗
PubMed2006

Assessing heterogeneity in meta-analysis: Q statistic or I2 index?

In meta-analysis, the usual way of assessing whether a set of single studies is homogeneous is by means of the Q test. However, the Q test only informs meta-analysts about the presence versus the absence of heterogeneity, but it does not report on the extent of such heterogeneity. Recently, the I(2) index has been proposed to quantify the degree of heterogeneity in a meta-analysis. In this article, the performances of the Q test and the confidence interval around the I(2) index are compared by means of a Monte Carlo simulation. The results show the utility of the I(2) index as a complement to the Q test, although it has the same problems of power with a small number of studies.

Analysis of Variance↗
PubMed2002

Impact of interviewer's body mass index on underreporting energy intake in overweight and obese women.

OBJECTIVE: To determine if overweight and obese women provide more accurate reports of their energy intake by 1) in-person recall with an obese interviewer, 2) in-person recall with a lean interviewer, or 3) telephone recall with an unknown interviewer. RESEARCH METHODS AND PROCEDURES: Eighty-eight overweight and obese women participated in this study. Subjects completed one telephone-administered multiple-pass 24-hour recall (MP24R) with an unknown interviewer and were then randomly assigned to an in-person MP24R with either a lean or obese interviewer to gather reported energy intake (rEI). Basal metabolic rate (BMR) was measured using a Deltrac monitor, and physical activity (EEPA) was estimated using a Caltrac accelerometer. Therefore, estimated energy expenditure was determined by: estTEE = (BMR + EEPA) x 1.10. RESULTS: No significant differences were found between the two in-person interview modes for subject age, weight, body mass index, percentage of body fat, total energy expenditure, rEI, and misreporting of energy intake. In-person recall data were combined for comparison with the telephone recalls. No significant difference was found between the in-person and telephone recalls for rEI and misreporting. Mean reported energy intake was significantly lower than estimated total energy expenditure for the telephone recalls and combined (lean and obese modes) in-person recalls. CONCLUSIONS: This study found that interviewer body mass index had no impact on self-reported energy intake during an in-person MP24R, and that telephone recall data were comparable with in-person recalls. Underreporting was a widespread problem ( approximately 26%) for all modes in this sample.

Adult↗
PubMed1995

The effectiveness of the cervical halo: open versus closed ring. A preliminary report.

The halo cervical orthosis has proven extremely effective in stabilizing the spine, both non-operatively and as a supplement to operative procedures. Current designs of the available halo utilize either a closed or an open stabilizing ring. Twenty-four patients with various indications for halo application are reviewed. Eleven were treated with a closed ring apparatus (Ace Medical, Los Angeles, California), and thirteen with an open ring device (Bremer, Inc, Jacksonville, Florida). X-rays of the treated patients were compared by group, and patients were interviewed regarding their complaints while wearing the halo. Rates of complication were compared. Results showed no significant differences between radiographs (kyphosis or translation) throughout the follow-up period. Patients experienced a significantly higher incidence of halo-associated pain in the open group. Otherwise, there were no statistical differences in the complication rates of either device. Whether or not the higher incidence of pain in the open group is related to decreased device rigidity is unknown. The open design may theoretically permit bending and opening of the ring to occur, the so-called 'wishbone' effect. Based on these data, it cannot be determined whether the advantages of the open ring--ease of application--are offset by this potential disadvantage. Clearly, a larger, randomized prospective study is required to investigate this.

Adolescent↗
PubMed2003

Comparison of telephone vs face-to-face interviews in the assessment of dietary intake by the 24 h recall EPIC SOFT program--the Norwegian calibration study.

OBJECTIVE: To compare food group intakes in grams, total energy and energy contribution from macronutrients between two random samples of women, using a standardized computer program (EPIC SOFT) with either a face-to-face or a telephone 24 h recall interview design. METHODS: Two groups of Norwegian women living in Tromsø were drawn at random from the Norwegian Women and Cancer Study (NOWAC) cohort. The EPIC SOFT computer program was used to conduct single 24 h dietary recalls either by telephone or face to face. For the latter, 160 women were invited, of whom 111 responded positively (crude response rate=69.4%) and 102 were interviewed. For the telephone option, 180 were invited to participate, 109 responded positively (crude response rate=60.6%) and 103 were interviewed. RESULTS: The two groups of women were similar with respect to age, body mass index, basal metabolic rate, smoking, education, physical activity and special diet status. No statistically significant difference in dietary intake was found between interviews conducted by telephone and face-to-face, except for 'egg and egg products' (P<0.01), for which intake was higher in the telephone group. Total energy intake differed, but the difference was attributable to one interviewer. The distribution of energy-contributing nutrients was not significantly different between groups, except for reported energy percentage from protein (P=0.02), which was significantly higher in the face-to-face group. CONCLUSION: The telephone vs face-to-face interview design did not influence recalled diet when using the EPIC SOFT program.

Calibration↗
PubMed2003

Computerization of a dietary history interview in a running cohort; evaluation within the Amsterdam Growth and Health Longitudinal Study.

OBJECTIVE: In nutritional research, a growing interest in the use of computer-assisted cross-check dietary history interview methods exists in order to improve cost-effectiveness. The introduction of such a method in an ongoing longitudinal study was evaluated with special emphasis on the effect on interviewer bias. DESIGN: A study for the interviewer bias within and the agreement between a previously used paper-based face-to-face cross-check dietary history interview method and a newly developed interviewer-administered computer-assisted version of this interview method. SUBJECTS: The interviewer bias of 436 face-to-face interviews is compared with that of 352 computer-assisted interviews. A subset of 82 subjects underwent a face-to-face interview at the mean age of 27 and 32 y and a computer-assisted interview at their mean age of 36 y. Energy, three macronutrients (protein, fat and carbohydrate), two micronutrients (calcium and iron) and alcohol intakes obtained by these three measurements are compared to analyse the agreement between the two interview methods. RESULTS: ANOVA showed no interviewer bias for all seven analysed nutrients within the data from the computer-assisted interview, while for the face-to-face interview method, several nutrients varied significantly among the interviewers. Five different measures, used to analyse the agreement (differences, Pearson's correlation, ICC, square weighted kappa and Bland-Altman plots), showed no relevant differences between the two cross-check dietary history interview methods. CONCLUSIONS: It is concluded that the computer-assisted interview caused a reduction of interviewer bias and is of similar quality to the face-to-face interview method. Computerization of a paper-based interview can be implemented in a running cohort if a change in method is unavoidable.

Adult↗
PubMed2002

Power dressing and meta-analysis: incorporating power analysis into meta-analysis.

AIMS: This paper highlights the lack of consideration that is given to power in the health and social sciences, which is a continuing problem with both single study research and more importantly for meta-analysis. BACKGROUND: The power of a study is the probability that it will lead to a statistically significant result. By ignoring power the single study researcher makes it difficult to get negative results published and therefore affects meta-analysis through publication bias. Researchers using meta-analysis, who also ignore power, then compound the problem by including studies with low power that are more likely to show significant effects. METHOD: A simple means of calculating an easily understood measure of effect size from a contingency table is demonstrated in this paper. A computer programme for determining the power of a study is recommended and a method of reflecting the adequacy of the power of the studies in a meta-analysis is suggested. An example of this calculation from a meta-analytic study on intravenous magnesium, which produced inaccurate results, is provided. CONCLUSION: It is demonstrated that incorporating power analysis into this meta-analysis would have prevented misleading conclusions being reached. Some suggestions are made for changes in the protocol of meta-analytic studies, which highlight the importance of power analysis.

Bias↗
PubMed2001

Hawthorne effects and research into professional practice.

The Hawthorne studies in the 1930s demonstrated how difficult it is to understand workplace behaviour, and this includes professional performance. Studies of interventions to improve professional performance, such as audit, can provide useful information for those considering using such methods, but cannot replace judgement. In particular, there is no single phenomenon that can be labelled 'the Hawthorne effect'. The process of triangulation, considering a subject from different perspectives, might overcome the problems of Hawthorne effects better than using a single method such as controlled trials.

Effect Modifier, Epidemiologic↗
PubMed2003

Social network as a moderator in the relation between trauma exposure and trauma reaction: a survey among UN soldiers and relief workers.

Social network as a moderator between trauma exposure and post-trauma symptomatology was studied. Two samples--relief workers and UN soldiers--were assessed on trauma exposure, social network and three dependent measures related to post-trauma reactions. Regression analysis and interaction plots were used to determine the presence of interaction effects between trauma exposure and social network. All four network variables moderated the relationship between trauma exposure and post-trauma reactions among relief workers, while among UN soldiers only two such buffer effects were found. Furthermore, among UN soldiers one of these interaction effects was reversed, indicating social support to be important for those low on trauma exposure, while among relief workers support was important in the high-exposure condition. The results indicate a difference with respect to the importance of social network as a moderator between groups exposed to different kinds of war trauma. Differences in motivational systems may also exist. However, further research will have to establish this.

Adult↗