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PubMedDate not supplied

Selection of ecologic covariates in the American Cancer Society study.

The American Cancer Society (ACS) Study of the effects of long-term exposure to ambient air pollution on mortality used metropolitan areas to assign exposures to individual cohort members (Pope et al., 1995); these authors did not, however, control for any other place-specific variables in their analysis. Consequently, the study has been criticized on the basis that the association observed between air pollution and mortality may be confounded by other unmeasured ecologic covariates. To address this criticism, the reanalysis team selected a set of place-specific variables that measured determinants of health ranging from the biophysical environment to the social environment and the healthcare system. This article outlines the process by which place-specific ecologic covariates were selected; data measuring these variables were obtained and geographic boundaries for places were delineated. Issues involved in obtaining and using geographically based ecological data are examined within the context of the reanalysis of the ACS study. Both the ecological fallacy and the atomistic fallacy are addressed and an argument is made for the importance of studying the effects of place-specific variables that are integral or contextual in nature. Issues relating to the Modifiable Areal Unit Problem (MAUP) are explored with reference to using ZIP codes and data from a variety of sources. It is argued that differences in the geographical scale of variability for various pollutants may prove to be the key to distinguishing between their relative impacts on health and that multilevel analyses are essential for understanding the impact of social and environmental determinants of health. A number of determinants of health are then briefly examined in terms of their association with mortality, the appropriateness of their being measured at the metropolitan scale, and the availability of data for the 1980s from U.S. sources. Finally, the article presents the database of place-specific ecologic covariates that was incorporated into the ACS models during the reanalysis in order to account for the influence that place may have above and beyond ambient air pollution.

Air Pollutants↗
PubMed2001

Breast cancer and hormone replacement therapy: putting the risk into perspective.

Data on hormone replacement therapy and breast cancer risk come from a number of observational studies (mostly American studies). Those published up to 1995 were reanalyzed by the Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC). They involved populations where exceedingly high estrogen doses were used as first-line therapy, and a progestin was added in a minority of women. Overall, the CGHFBC reanalysis found that the relative risk increased by 0.023 for each year of use (with an absolute excess risk of two or six cases out of 1000 women treated for 5 or 10 years, respectively). Further American studies, published in 2000 and involving populations where lower doses were used, showed a risk increase of 0.01 per year of estrogen-only use. Both the CGHFBC reanalysis and the further studies did not find an increase of risk in treated overweight women. Possibly, overweight women already have a maximal estrogenic stimulus on the breast due to extraglandular estrogen production. An additional explanation could be that oral estrogens, through their hepatocellular effects, reverse some biological features of obesity (e.g. decreased sex hormone binding globulin level and increased insulin-like growth factor-I bioactivity) that potentially increase breast cancer risk, so balancing the estrogen stimulation. The CGHFBC reanalysis did not show a substantial difference in breast cancer risk between the majority using estrogen alone and the small minority using estrogen plus progestin. Conversely, Swedish studies and the recent American studies suggest that the risk increase could be higher with the addition of a progestin, compared with estrogen-only use. The biological effect of progesterone/progestins on the breast tissue is controversial. Even if the observed increase in risk could be partially ascribed to non-progesterone-like effects of some progestins (e.g. opposing the hepatocellular effects of oral estrogens) and also (in the American studies) to use-bias, a detrimental action due to progesterone-like effects cannot be excluded. However, the theoretical possibility exists that low doses of oral estrogens, plus a progestin providing progesterone-like effects only, will be shown to be associated with a limited breast cancer risk increase.

Breast Neoplasms↗
PubMed1997

When syntax meets semantics.

Three experiments concerning the processing of syntactic and semantic violations were conducted. Event-related potentials (ERPs) showed that semantic violations elicited an N400 response, whereas syntactic violations elicited two early negativities (150 and 350 ms) and a P600 response. No interaction between the semantic and early syntactic ERP effects was found. Sentence complexity and violation probability (25% vs. 75%) affected only the P600 and not the early negativities. The probability effect was taken as evidence that the P600 resembles the P3b. The temporal order of word processing in a sentence as suggested by the data was such that a more automatic syntactic analysis was performed (earlier syntactic-related negativities) in parallel with a semantic analysis (N400), after which a syntactic reanalysis was performed (P600). A reanalysis interpretation of the P600 could explain why the extent of the reanalysis differed with syntactic complexity and probability of ungrammaticality.

Adult↗
PubMed2006

Estimating the effect of smoking cessation on weight gain: an instrumental variable approach.

OBJECTIVE: To propose and test a method that produces an unbiased estimate of the average effect of smoking cessation on weight gain. Previous estimates may be biased due to unobservable differences in attributes of quitters and continuing smokers. An accurate estimate of weight gain due to cessation is important for policymakers, health managers, clinicians, consumers, and developers of smoking cessation aids. STUDY SETTING: Our analysis consisted of an instrumental variables (IVs) approach in which treatment assignment in randomized smoking cessation trials served as a random source of variation in probability of quitting. DATA COLLECTION: We searched the medical literature for previously conducted smoking cessation trials that contained data suitable for our reanalysis. PRINCIPAL FINDINGS: We identified one trial for our reanalysis, the Lung Health Study, a randomized smoking cessation trial with 5,887 smokers aged 35-60 from 1986 to 1994 in several sites across the United States. In our IV reanalysis, we estimated a 9.7 kg weight gain over 5 years due to cessation, as compared with the conventional estimate of 5.3 kg. CONCLUSIONS: The true effect of smoking cessation on weight gain may be larger than previously estimated. This result indicates the importance of fully understanding the possible weight effects of cessation and underscores the need to accompany cessation programs with weight management interventions. The result, however, does not overturn the conclusion that the net health benefits of quitting are positive and very large. The application of the IV technique we propose is likely to be useful in a variety of contexts in which one is interested in the effect of one health condition on another.

Adult↗
PubMedDate not supplied

A nurse-statistician reanalyzes data from the Rosa therapeutic touch study.

This article presents a reanalysis of data used to support the work of Emily Rosa's Therapeutic Touch (TT) science fair project published as an article in the Journal of the American Medical Association (JAMA) in 1998. The purpose of this article is to take a closer look at the assumptions, data, statistical procedures, and conclusions of the JAMA article. This is accomplished by focusing on (1) the conclusion that there was no overall effect of TT, (2) the conclusion that TT practitioners did not perform better depending on which hand was used, and (3) the assumptions about the capability of Rosa's experiment to validate an existing skill. Reanalysis of the Rosa data suggests contradictions to the authors' conclusions. Based on this reanalysis, the authors' recommendations against the use of TT can and should be challenged because of inappropriate design and analysis as well as incorrect statistical assumptions and conclusions.

Confidence Intervals↗
PubMed2006

Estimating transfer of learning for self-instructional packages across dental schools.

The most common topic of research in dental education is assessing the effectiveness of self-instructional units in various formats compared to lectures covering the same material. Generally, these studies are of high methodological quality and reveal mixed results or results slightly favoring self-instruction. All such studies, save one, have been conducted in the context of various single schools, thus confounding the effects of self-instructional format with factors particular to schools and their students. A reanalysis, using Cronbach's generalizability analysis, was performed on a study in the literature that was conducted at six schools and measured student aptitude. The reanalysis found that the largest source of variance on immediate post-test quizzes for knowledge following a three-hour unit on disturbances in tooth development was the school at which the study was conducted (24 percent), followed by student aptitude measured by DAT score (20 percent). Difference in format among lecture, booklet, and audiotape presentations accounted for 5 percent of the variance. This reanalysis demonstrated that statistically significant results from rigorous experimental designs can overrepresent what is revealed by such research. The context-specificity of educational innovations may be underestimated because few studies are replicated across schools. Studies conducted as single schools, regardless of their methodological rigor, fail to address issues associated with potential transfer of findings to other schools.

Analysis of Variance↗
PubMed1985

Asbestos and gastrointestinal cancer. A review of the literature.

Exposure to asbestos is among several factors cited as possible causes of esophageal, gastric and colorectal cancer. More than 45 published studies have presented mortality data on asbestos-exposed workers. For each cohort, we listed the observed and expected rates of deaths from types of gastrointestinal cancer based on the latest published follow-up. Summary standardized mortality ratios (SMRs) were then derived. Finally, we calculated summary SMRs for total gastrointestinal tract cancer for three occupational groups: asbestos factory workers, insulators/shipyard workers and asbestos miners. Statistically significant elevations in summary SMRs were found for esophageal, stomach and total gastrointestinal tract cancer in all asbestos-exposed workers. Esophageal cancer summary SMRs remained significantly elevated when data were reanalyzed to include only those cohorts with death certificate diagnoses for cause of observed deaths. However, summary SMRs were not statistically significant for stomach and total gastrointestinal tract cancer after reanalysis. Summary SMRs by occupational group showed a significant elevation for total gastrointestinal cancer in insulators/shipyard workers. The elevation was not significant after reanalysis. Based on the results after reanalysis, the elevations in summary SMRs for stomach and total gastrointestinal tract cancer are of a magnitude that could result from diagnostic and investigator error. We conclude that more studies are required before stomach and colorectal cancers are documented as asbestos-related diseases.

Asbestos↗
PubMed1997

A strategy to reduce healthy worker effect in a cross-sectional study of asthma and metalworking fluids.

This report describes the reanalysis of a cross-sectional study of asthma in a large cohort of autoworkers with exposure to metalworking fluids (MWF). There is strong evidence from case reports, clinical studies, and medical surveillance data that exposure to MWF can cause asthma, yet no association was found in the original analysis. The central hypothesis of the reanalysis was that the absence of an association between asthma and MWF exposure was the result of bias caused by the self-selection of asthmatics out of exposed jobs. We addressed the potential job transfer bias by redefining exposure and disease status at the time of asthma onset, rather than at the time of the health survey. This permitted us to treat the cross-sectional study as if it were a historical cohort study, despite the fact that the population was a biased sample of the full cohort. This approach resulted in a significantly elevated incidence rate ratio of 3.2 (95% CI: 1.2-8.3) for synthetic MWF estimated in a Cox proportional hazards model. Although the cross-sectional design makes it impossible to document or control for differential selection out of the workforce, the approach described here provides a strategy for reducing the healthy-worker effect due to job transfer bias in cross-sectional studies.

Adult↗
PubMedDate not supplied

Point of diminishing returns: when does gestational weight gain cease benefiting birthweight and begin adding to maternal obesity?

This study is a reanalysis of the first scientific paper published by one of the authors, originally coauthored with Dr. Roy H. Petrie. In honor of Dr. Petrie, these data have been reanalyzed to re-evaluate the data using more sophisticated techniques and to expand on the original findings. This reanalysis examines the contribution of maternal weight gain to infant birthweight and retained maternal weight in the immediate postpartum period, and the effect of weight gains below, at, and above the Institute of Medicine (IOM) guidelines on both infant birthweight and retained maternal weight in the postpartum period. The study population included 487 term, uncomplicated, singleton pregnancies. Body mass index (BMI) was calculated for each woman, and categorized as underweight, normal weight, or overweight. Maternal retained weight was calculated as postpartum weight 2 days after delivery minus pregravid weight. Every kilogram of gestational weight gain increased birthweight by 44.9 g for underweight women, 22.9 g for normal weight women, and 11.9 g for overweight women. For every kilogram of retained weight, birthweight was increased by 35.6 g for underweight women, 15.9 g for normal-weight women, and 5.1 g for overweight women. Increasing weight gains from below to equal to IOM guidelines increased birthweight and maternal retained weight by 317 g (11%) (P < 0.01) and 5 kg (P < 0.01), respectively, for underweight women; 141 g (4.4%) (P < 0.02) and 6.2 kg (P < 0.01), respectively, for normal-weight women; and 200 g (6.4%) (NS) and 6.4 kg (P < 0.01), respectively, for overweight women. Increasing weight gains from equal to above the IOM guidelines increased birthweight and maternal retained weight by an additional 299 g (9.4%) (P < 0.02) and 7.3 kg (P < 0.01), respectively, for underweight women; an additional 196 g (5.9%) (P < 0.01) and 5.9 kg (P < 0.01), respectively, for normal weight women; and an additional 9 g (0.3%) (NS) and 8.3 kg (P < 0.01), respectively, for overweight women. These findings suggest that, beyond a certain level of weight gain, there is a point of diminishing returns (increase in birthweight) at the expense of increasing maternal postpartum obesity for the woman who has gained excessively.

Adult↗
PubMed1992

Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers.

We previously reported on the lung cancer mortality through 1983 of 760 males who were diagnosed with silicosis during 1930-1983 by the State of North Carolina's medical examination program for dusty trades workers. The lung cancer SMR (95% confidence interval) was 2.6 (1.8-3.6) among 655 white members of this group. In this paper, we report the results of a reanalysis of mortality among a subgroup for whom chest radiographs were currently available for rereading. Technically acceptable radiographs were available for 306 white males and were independently reclassified for pneumoconiosis by 3 "B" readers using the 1980 ILO Classification. Lung cancer SMRs were 1.7 (0.8-3.1) for the entire group of 306 white males, 2.5 (1.1-4.9) for 143 subjects reclassified as simple silicosis, and 1.0 (0.1-3.5) for 96 subjects whose radiographs were reclassified as ILO category 0. There were no lung cancer deaths among 67 subjects whose radiographs were reclassified as progressive massive fibrosis. Corresponding lung cancer SMRs for subjects who had never been employed in a job with exposure to known occupational carcinogens were 1.2 (0.2-4.4) for those reclassified as category 0, and 2.4 (1.0-5.0) for those reclassified as having simple silicosis. The age-adjusted lung cancer rate ratio among subjects with simple silicosis compared to those with category 0 was 1.5 (0.4-5.8). Our findings from this reanalysis, which effectively controls for misclassification of silicosis due to errors in radiograph interpretation by North Carolina program readers, offer additional evidence consistent with the hypothesis of an association between silicosis and lung cancer in this study group.

Adult↗
PubMed1997

Cerebellar hypermetria: reduction in the early component of the antagonist electromyogram.

Several articles have described the electromyographic (EMG) patterns underlying cerebellar hypermetria. However, the description of the EMG associated with hypermetria is not consistent between studies. It is hypothesized that the reason for this concerns the criteria used to define and describe the antagonist latency. Several studies on neurologically normal individuals have shown that there are two components to the antagonist EMG: an early component and a late component. However, many studies have identified only one component and have not defined whether it was the early or late component. A reanalysis of one published data set that had previously identified only one antagonist component was performed. The reanalysis suggests that hypermetria can be caused by an absence of an early antagonist EMG component, a delayed late component, or both. In addition, a new measure is suggested that allows this hypothesis to be further evaluated.

Cerebellar Diseases↗
PubMed2001

Thematic roles assigned along the garden path linger.

In the literature dealing with the reanalysis of garden path sentences such as While the man hunted the deer ran into the woods, it is generally assumed either that people completely repair their initial incorrect syntactic representations to yield a final interpretation whose syntactic structure is fully consistent with the input string or that the parse fails. In a series of five experiments, we explored the possibility that partial reanalyses take place. Specifically, we examined the conditions under which part of the initial incorrect analysis persists at the same time that part of the correct final analysis is constructed. In Experiments 1a and 1b, we found that both the length of the ambiguous region and the plausibility of the ultimate interpretation affected the likelihood that such sentences would be fully reanalyzed. In Experiment 2, we compared garden path sentences with non-garden path sentences and compared performance on two different types of comprehension questions. In Experiments 3a and 3b, we constructed garden path sentences using a small class of syntactically unique verbs to provide converging evidence against the position that people employ some sort of "general reasoning" or pragmatic inference when faced with syntactically difficult garden paths. The results from these experiments indicate that reanalysis of such sentences is not always complete, so that comprehenders often derive an interpretation for the full sentence in which part of the initial misanalysis persists. We conclude that the goal of language processing is not always to create an idealized structure, but rather to create a representation that is "good enough" to satisfy the comprehender that an appropriate interpretation has been obtained.

Cognition↗
PubMed1995

In search of butterfly origins.

To determine the sister taxon to butterflies, the relationships among the macrolepidopteran superfamilies were investigated using sequence data from the ND1 gene of mitochondrial DNA. Both sequence data and translated amino acids were used. We examined how different models of amino acid evolution (nonadditive) affected the inference of tree topology. We then added previously published sequence data from the 18S and 28S subunits of ribosomal RNA. In most analyses, regardless of data type and treatment, the Hedyloidea is either the sister taxon to butterflies or derived within the butterfly clade. These molecular results are compared to a reanalysis of morphological characteristics. The reanalysis of morphology agrees with Minet's 1991 hypothesis of hedyloid relationships. Analysis of combined molecular and morphology data supports the hypothesis that hedylids are the sister group to butterflies. Scott's hypothesis that hawk moths (Sphingidae) are the sister taxon to butterflies is discounted.

Amino Acid Sequence↗
PubMed1999

The Tromsø Study: artifacts in forearm bone densitometry--prevalence and effect.

Suboptimal performance of bone densitometer, operator and/or subject may cause artifacts of consequence both for individual patient management and research. The prevalence and effects of such artifacts are largely unknown in densitometry. A cross-sectional population-based study was carried out of artifacts in forearm bone densitometry with single X-ray Absorptiometry (SXA) of the nondominant hand (distal and ultradistal site). After the screening, all scans were reviewed for artifact detection and reanalysis. The effect on the bone mineral density (BMD) result was found by comparing artifactual scans with a reanalyzed version or with normal repeat scans. All women aged 50-74 years, all men aged 55-74 years and 5-10% samples of other age groups aged >/=25 years attending the fourth Tromso health study were invited to have bone densitometry. The response rate from the background population was 80% (n = 7948). Fourteen percent of subjects had a movement artifact at either the distal or ultradistal site. The individual BMD variation was twice as large in scans with a movement artifact (0.94%) compared with normal scans (0.58%) (p = 0.0027). The radial endplate was inaccurately detected in 74% of the scans. Reanalysis of these scans led to a mean 3.8% decrease in the BMD value and an increase in the prevalence of osteoporosis of 10%. Artifacts were thus common, and their effects were clinically relevant in forearm bone densitometry. Artifacts and their effects need to be characterized in other bone densitometry settings also.

Absorptiometry, Photon↗
PubMed1985

The use of polytomous dual response data to increase power in case-control studies: an application to the association between dietary fat and breast cancer.

Computer simulation has been used to compare various methods for analyzing data from case-control studies when two response variables are available to measure a risk factor. When such variables are continuous or polytomous, and a dose-response relationship exists, it is concluded that power may be increased by including individuals who are discordant on their responses. Failure to use the most appropriate method can lead to a substantial loss in power. The results are illustrated by reanalysis of data from an earlier case-control study of diet and breast cancer. This reanalysis has strengthened the evidence for a positive association between saturated fat intake and risk of breast cancer, with some suggestion that this association is limited to premenopausal women, in whom the increase in risk may be substantial.

Breast Neoplasms↗
PubMed1981

The nondeviant nature of deviant phonological systems.

Few studies of children with defective speech or deviant phonologies have gone beyond the level of phonetic representation in limited environments. The Lorentz (1976) study of Joe, a 4.5-yr-old child with a phonological disorder, is exceptional inasmuch as underlying phonemic representations and phonological rules are posited in addition to the surface phonetic representations. However, his analysis crucially depends on morphosyntactic information that cannot be independently justified. A reanalysis of Joe's data within Kahn's (1976) syllable-based model of generative phonology reveals that the child's phonological rules are syllabically conditioned exclusively. In particular, the application of certain rules is found to depend on whether or not an internal syllable boundary is present within a polysyllabic word. In the course of the reanalysis, issues concerning naturalness of individual phonological rules, ordering relations between pairs of rules, feature systems, the phonological representation of double-articulated consonants, and the role of the syllable as element in phonological descriptions are discussed. Paradoxically, Joe's phonological system is found to be "normal," as measured in terms of the above-mentioned linguistic parameters, yet his speech output is "abnormal," as measured against the adult norm.

Child, Preschool↗
PubMed1978

A critique of the collaborative cytogenetics study to measure and minimize interlaboratory variation.

A statistical reanalysis was performed on the data fecently reported on a 6-laboratory, collaborative cytogenetic study to measure and minimize interlaboratory variation. Three of the laboratories had mean values significantly different from the others on most of the 6 indexes of chemically-induced aberration; one laboratory with values higher and two with values lower. Furthermore, relative variability of the values around the means was consistently lower in one of the 6 participating laborabories. The results of the reanalysis of this collaborative study demonstrates that significant interlaboratory differences exist and that these should be adjusted or diminished before rat cytogenetic analysis can be an effective test system for evaluation of a compound for mutagenic potential.

Animals↗
PubMed1987

Interindividual variability of lithium-induced EEG changes in healthy volunteers.

A placebo-controlled, double-blind study on the effects of lithium on the electroencephalogram (EEG) was performed in 20 healthy volunteers. A reanalysis of the data which previously had been evaluated by factor analysis and other techniques is presented. The aim of this reanalysis is a quantitative reconstruction of visually defined vigilance stages. In 8 of the 10 healthy subjects who received lithium, a "stabilization" of vigilance on a slightly lowered level (i.e., increased continuity of alpha activity and a tendency in the direction of increased alpha anteriorization) could be demonstrated after a 2-week medication period (mean lithium plasma level: 0.65 mmol/l), indicating that in these subjects lithium counteracts the physiological decline of vigilance to be expected under resting conditions. The interpretation of this finding as a reduction of physiological variability, or as a "dynamic restriction," corresponds to findings in other areas of lithium research which can be interpreted in an analogous manner. In two subjects, however, a small decline of vigilance was observed. These two subjects showed an especially pronounced alpha rhythm in their predrug EEG compared with the other volunteers. The authors discuss whether the delineation of different EEG reaction types contributes to the responder problem in lithium research.

Adult↗