Abstract:
:Multivariate finite mixture models have been applied to the identification of dietary patterns. These models are known to have many parameters, and consequently large samples are usually required. We present a special case of a multivariate mixture model that reduces the number of parameters to be estimated and seems adequate for small to moderately sized samples. We illustrate our approach with an analysis of Portuguese data from a food-frequency questionnaire and with a simulation study.
journal_name
Stat Medjournal_title
Statistics in medicineauthors
Rita Gaio A,Costa JP,Santos AC,Ramos E,Lopes Cdoi
10.1002/sim.5336subject
Has Abstractpub_date
2012-08-30 00:00:00pages
2137-50issue
19eissn
0277-6715issn
1097-0258journal_volume
31pub_type
杂志文章abstract::We propose to use a very simple model to test whether a cancer cluster is due to chance alone. We focus on the acute childhood leukaemia cluster in Columbus, Ohio. In 1975, 12 leukaemia cases were observed in Columbus while the expected number is 6 cases per year. According to our simple model, the probability of such...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/1097-0258(20000830)19:16<2195::aid-sim522>
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abstract::We provide a Bayesian analysis of data categorized into two levels of age (younger than 50 years, at least 50 years) and three levels of bone mineral density (normal, osteopenia, osteoporosis) for white females at least 20 years old in the third National Health and Nutrition Examination Survey. For the sample, the age...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1985
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abstract::In order for national statistical offices to maintain the trust of the public to collect data and publish statistics of importance to society and decision-making, it is imperative that respondents (persons or establishments) be guaranteed privacy and confidentiality in return for providing requested confidential data....
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abstract::This paper models monthly AIDS diagnosis counts in terms of smooth secular trend, calendar month effects, and the number of workdays per month. A parameterization of month effects allows separation of true seasonal effects from a linear trend over the calendar year and an arbitrary June effect. There is strong evidenc...
journal_title:Statistics in medicine
pub_type: 杂志文章
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abstract::We examine the common clinical belief that there is an interaction between epilepsy type and the two standard anti-epileptic drugs, valproate and carbamazepine, using data from several randomized clinical trials. Epilepsy type is not always easy to define, and three possible reclassifications are investigated to see w...
journal_title:Statistics in medicine
pub_type: 杂志文章,meta分析
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abstract::Clinical trials utilizing predictive biomarkers have become a research focus in personalized medicine. We investigate the effects of biomarker misclassification on the design and analysis of stratified biomarker clinical trials. For a variety of inference problems including marker-treatment interaction in particular, ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.6164
更新日期:2014-08-15 00:00:00
abstract::Many studies have reported large variations in age- and sex-adjusted rates of hospitalizations across small geographic areas. These variations have often been attributed to differences in medical practice style which are not reflected in differences in health care outcomes. There is, however, another potentially impor...
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abstract::In monitoring a clinical trial or other observational study with a survival endpoint, sometimes the numbers of patients entering and dying at each time point are presented, but the connections between them are kept confidential. Hence, the exact time to failure or censoring for each individual is missing. We refer to ...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2819
更新日期:2007-08-30 00:00:00
abstract::The two-period cross-over design with two sequences of drug administration is a standard experimental design when bioequivalence of one test formulation is to be assessed in comparison with a reference formulation. Previously, an approach based on Fieller's confidence interval has been presented for the assessment of ...
journal_title:Statistics in medicine
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abstract::In a variety of biomedical applications, particularly those involving screening for infectious diseases, testing individuals (e.g. blood/urine samples, etc.) in pools has become a standard method of data collection. This experimental design, known as group testing (or pooled testing), can provide a large reduction in ...
journal_title:Statistics in medicine
pub_type: 杂志文章
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abstract::Comparative Poisson trials of prophylactic interventions, such as vaccines, can be lengthy and costly. We evaluate two easily implemented approaches to reduce numbers of disease cases and person years of follow up (N(u+t)) for comparative Poisson trials with fixed numbers of cases (T); (i) altering k the portion of N(...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.1724
更新日期:2004-04-30 00:00:00
abstract::Although the literature on contraceptive failure is vast and is expanding rapidly, our understanding of the relative efficacy of methods is quite limited because of defects in the research design and in the analytical tools used by investigators. Errors in the literature range from simple arithmetical mistakes to outr...
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journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.8724
更新日期:2020-12-10 00:00:00
abstract::Prediction performance of a risk scoring system needs to be carefully assessed before its adoption in clinical practice. Clinical preventive care often uses risk scores to screen asymptomatic population. The primary clinical interest is to predict the risk of having an event by a prespecified future time t0 . Accuracy...
journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.7606
更新日期:2018-05-10 00:00:00
abstract::The semi-Markov assumption emphasizes the importance of time spent in a state. In order to compute this type of multistate model, most transition times are always considered to be exactly identified or right censored. However, in the longitudinal analysis of chronic diseases, investigators are often confronted with in...
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doi:10.1002/sim.3100
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pub_type: 信件
doi:10.1002/sim.8669
更新日期:2020-11-30 00:00:00
abstract::A statistical analysis is presented of the intensities of admissions to psychiatric hospitals among women in Denmark who either gave birth to a child in the year 1975 or had an induced abortion in the same year. The models used are time-continuous Markov and semi-Markov processes, and the methods employed include non-...
journal_title:Statistics in medicine
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pub_type: 杂志文章
doi:10.1002/sim.3524
更新日期:2009-04-15 00:00:00
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journal_title:Statistics in medicine
pub_type: 杂志文章
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journal_title:Statistics in medicine
pub_type:
doi:10.1002/sim.2045
更新日期:2004-11-30 00:00:00
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journal_title:Statistics in medicine
pub_type: 杂志文章
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更新日期:2017-07-30 00:00:00
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journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.2773
更新日期:2007-07-10 00:00:00
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journal_title:Statistics in medicine
pub_type: 杂志文章
doi:10.1002/sim.4393
更新日期:2012-02-28 00:00:00
abstract::Korn and Whittemore have presented methods for analyzing longitudinal data where the number of observations per individual is large relative to the number of variables considered for each subject. However, this is often not the case in epidemiologic studies, since one usually collects data at relatively few time point...
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