Variance constraints strongly influenced model performance in growth mixture modeling: a simulation and empirical study.

abstract：BACKGROUND:Physical activity is an important determinant of health. Walking is the most common physical activity performed by adults and the presence of sidewalks along roads is a determinant of walking. Geographic information systems (GIS) can be used to measure sidewalks; however, GIS sidewalk data are difficult to a...

journal_title：BMC medical research methodology

authors： Janssen I,Rosu A

更新日期：2012-03-29 00:00:00

abstract：BACKGROUND:Mediation is an important issue considered in the behavioral, medical, and social sciences. It addresses situations where the effect of a predictor variable X on an outcome variable Y is explained to some extent by an intervening, mediator variable M. Methods for addressing mediation have been available for ...

journal_title：BMC medical research methodology

authors： Knafl GJ,Knafl KA,Grey M,Dixon J,Deatrick JA,Gallo AM

更新日期：2017-03-21 00:00:00

abstract：BACKGROUND:A key component of the implementation process is identifying potential barriers and facilitators that need to be addressed. The Theoretical Domains Framework (TDF) is one of the most commonly used frameworks for this purpose. When applying the TDF, it is critical to understand the context in which behaviours...

journal_title：BMC medical research methodology

authors： Etherington N,Rodrigues IB,Giangregorio L,Graham ID,Hoens AM,Kasperavicius D,Kelly C,Moore JE,Ponzano M,Presseau J,Sibley KM,Straus S

更新日期：2020-06-26 00:00:00

abstract：BACKGROUND:Multistate models have become increasingly useful to study the evolution of a patient's state over time in intensive care units ICU (e.g. admission, infections, alive discharge or death in ICU). In addition, in critically-ill patients, data come from different ICUs, and because observations are clustered int...

journal_title：BMC medical research methodology

authors： Liquet B,Timsit JF,Rondeau V

更新日期：2012-06-15 00:00:00

abstract：BACKGROUND:Thresholds for statistical significance are insufficiently demonstrated by 95% confidence intervals or P-values when assessing results from randomised clinical trials. First, a P-value only shows the probability of getting a result assuming that the null hypothesis is true and does not reflect the probabilit...

journal_title：BMC medical research methodology

authors： Jakobsen JC,Gluud C,Winkel P,Lange T,Wetterslev J

更新日期：2014-03-04 00:00:00

abstract：BACKGROUND:For practical reasons it is not easy to obtain fasting samples in large population health surveys. Non-fasting triglyceride (Tg) values are difficult to interpret. The authors compared the accuracy of statistically corrected non-fasting Tg values with true fasting values and estimated the misclassification o...

journal_title：BMC medical research methodology

authors： Sundvall J,Leiviskä J,Laatikainen T,Peltonen M,Salomaa V,Vanhala M,Korpi-Hyövälti E,Lauronen J,Alfthan G

更新日期：2011-05-10 00:00:00

abstract：BACKGROUND:The BSI-18 contains the three six-item scales somatization, depression, and anxiety as well as the Global Severity Index (GSI), including all 18 items. The BSI-18 is the latest and shortest of the multidimensional versions of the Symptom-Checklist 90-R, but its psychometric properties have not been sufficien...

journal_title：BMC medical research methodology

authors： Franke GH,Jaeger S,Glaesmer H,Barkmann C,Petrowski K,Braehler E

更新日期：2017-01-26 00:00:00

abstract：BACKGROUND:Retaining participants in cohort studies with multiple follow-up waves is difficult. Commonly, researchers are faced with the problem of missing data, which may introduce biased results as well as a loss of statistical power and precision. The STROBE guidelines von Elm et al. (Lancet, 370:1453-1457, 2007); V...

journal_title：BMC medical research methodology

authors： Karahalios A,Baglietto L,Carlin JB,English DR,Simpson JA

更新日期：2012-07-11 00:00:00

abstract：BACKGROUND:Within cancer care, dynamic evaluations of the loss in expectation of life provides useful information to patients as well as physicians. The loss of lifetime function yields the conditional loss in expectation of life given survival up to a specific time point. Due to the inevitable censoring in time-to-eve...

journal_title：BMC medical research methodology

authors： Jakobsen LH,Andersson TM,Biccler JL,El-Galaly TC,Bøgsted M

更新日期：2019-01-28 00:00:00

abstract：BACKGROUND:In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatmen...

journal_title：BMC medical research methodology

authors： Yamaguchi Y,Maruo K,Partlett C,Riley RD

更新日期：2017-07-19 00:00:00

abstract：BACKGROUND:In the era of evidence based medicine, with systematic reviews as its cornerstone, adequate quality assessment tools should be available. There is currently a lack of a systematically developed and evaluated tool for the assessment of diagnostic accuracy studies. The aim of this project was to combine empiri...

journal_title：BMC medical research methodology

authors： Whiting P,Rutjes AW,Reitsma JB,Bossuyt PM,Kleijnen J

更新日期：2003-11-10 00:00:00

abstract：BACKGROUND:Quantitative survey of research articles, as an application of bibliometrics, is an effective tool for grasping overall trends in various medical research fields. This type of survey has been also applied to infectious disease research; however, previous studies were insufficient as they underestimated artic...

journal_title：BMC medical research methodology

authors： Takahashi-Omoe H,Omoe K,Okabe N

更新日期：2009-10-06 00:00:00

abstract：BACKGROUND:Studies examining incident heart failure (HF) have been limited to select populations. To examine incident HF with broader generalizability, there is need to assemble a HF-free cohort using a geographically-diverse sample. We aimed to develop and validate a simple medication-based strategy for assembling a H...

journal_title：BMC medical research methodology

authors： Goyal P,Mefford MT,Chen L,Sterling MR,Durant RW,Safford MM,Levitan EB

更新日期：2020-03-04 00:00:00

abstract：BACKGROUND:Compliance is a critical issue for parental questionnaires in school based epidemiological surveys and high compliance is difficult to achieve. The objective of this study was to determine trends and factors associated with parental questionnaire compliance during respiratory health surveys of school childre...

journal_title：BMC medical research methodology

authors： Koshy G,Brabin BJ

更新日期：2012-04-20 00:00:00

abstract：BACKGROUND:In low-income settings, key outcomes such as biomarkers or clinical assessments are often missing for a substantial proportion of the study population. The aim of this study was to assess the extent to which Heckman-type selection models can create unbiased estimates in such settings. METHODS:We introduce t...

journal_title：BMC medical research methodology

authors： Koné S,Bonfoh B,Dao D,Koné I,Fink G

更新日期：2019-12-09 00:00:00

abstract：BACKGROUND:The construction of prediction intervals (PIs) for future body mass index (BMI) values of individual children based on a recent German birth cohort study with n = 2007 children is problematic for standard parametric approaches, as the BMI distribution in childhood is typically skewed depending on age. METHO...

journal_title：BMC medical research methodology

authors： Mayr A,Hothorn T,Fenske N

更新日期：2012-01-25 00:00:00

abstract：BACKGROUND:Syntheses of qualitative studies can inform health policy, services and our understanding of patient experience. Meta-ethnography is a systematic seven-phase interpretive qualitative synthesis approach well-suited to producing new theories and conceptual models. However, there are concerns about the quality ...

journal_title：BMC medical research methodology

authors： France EF,Ring N,Thomas R,Noyes J,Maxwell M,Jepson R

更新日期：2014-11-19 00:00:00

abstract：BACKGROUND:Claims databases are generally considered inadequate for obesity research due to suboptimal capture of body mass index (BMI) measurements. This might not be true for bariatric surgery because of reimbursement requirements and changes in coding systems. We assessed the availability and validity of claims-base...

journal_title：BMC medical research methodology

authors： Li X,Lewis KH,Callaway K,Wharam JF,Toh S

更新日期：2020-09-07 00:00:00

abstract：BACKGROUND:Participants in voluntary research present a different demographic profile than those who choose not to participate, affecting the generalizability of many studies. Efforts to evaluate these differences have faced challenges, as little information is available from non-participants. Leveraging data from a re...

journal_title：BMC medical research methodology

authors： Dahrouge S,Armstrong CD,Hogg W,Singh J,Liddy C

更新日期：2019-08-07 00:00:00

abstract：BACKGROUND:Bias in adolescent self-reported height and weight is well documented. Given the importance and widespread use of the National Longitudinal Study of Adolescent to Adult Health (Add Health) data for obesity research, we developed and tested the feasibility and validity of an empirically derived statistical co...

journal_title：BMC medical research methodology

authors： Liechty JM,Bi X,Qu A

更新日期：2016-09-22 00:00:00

abstract：BACKGROUND:The development of risk prediction models is of increasing importance in medical research - their use in practice, however, is rare. Among other reasons this might be due to the fact that thorough validation is often lacking. This study focuses on two Bayesian approaches of how to validate a prediction rule ...

journal_title：BMC medical research methodology

authors： Held U,Bové DS,Steurer J,Held L

更新日期：2012-07-20 00:00:00

abstract：BACKGROUND:The self-controlled case series (SCCS) is a useful design for investigating associations between outcomes and transient exposures. The SCCS design controls for all fixed covariates, but effect modification can still occur. This can be evaluated by including interaction terms in the model which, when exponent...

journal_title：BMC medical research methodology

authors： Hawken S,Potter BK,Little J,Benchimol EI,Mahmud S,Ducharme R,Wilson K

更新日期：2016-09-23 00:00:00

abstract：BACKGROUND:The Template for Intervention Description and Replication (TIDieR) checklist and guide was developed by an international team of experts to promote full and accurate description of trial interventions. It is now widely used in health research. The aim of this paper is to describe the experience of using TIDi...

journal_title：BMC medical research methodology

authors： Cotterill S,Knowles S,Martindale AM,Elvey R,Howard S,Coupe N,Wilson P,Spence M

更新日期：2018-01-18 00:00:00

abstract：BACKGROUND:Data on lifetime exposures are often self-reported in epidemiologic studies, sometimes many years after the relevant age. Validity of self-reported data is usually inferred from their agreement with measured values, but few studies directly quantify the likely effects of reporting errors in body size and rep...

journal_title：BMC medical research methodology

authors： Cairns BJ,Liu B,Clennell S,Cooper R,Reeves GK,Beral V,Kuh D

更新日期：2011-01-17 00:00:00

abstract：BACKGROUND:Compelled by the intuitive appeal of predicting each individual patient's risk of an outcome, there is a growing interest in risk prediction models. While the statistical methods used to build prediction models are increasingly well understood, the literature offers little insight to researchers seeking to g...

journal_title：BMC medical research methodology

authors： Schummers L,Himes KP,Bodnar LM,Hutcheon JA

更新日期：2016-09-21 00:00:00

abstract：BACKGROUND:To accurately predict the response to treatment, we need a stable and effective risk score that can be calculated from patient characteristics. When we evaluate such risks from time-to-event data with right-censoring, Cox's proportional hazards model is the most popular for estimating the linear risk score. ...

journal_title：BMC medical research methodology

authors： Omae K,Eguchi S

更新日期：2020-07-06 00:00:00

abstract：:The quality of a consultation provided by a physician can have a profound impact on the quality of care and patient engagement in treatment decisions. When the COPD Assessment Test (CAT) was developed, one of its aims was to aid the communication between physician and patient about the impact of COPD. We developed a n...

journal_title：BMC medical research methodology

authors： Gruffydd-Jones K,Marsden H,Holmes S,Kardos P,Escamilla R,Dal Negro R,Roberts J,Nadeau G,Leather D,Jones P

更新日期：2013-05-10 00:00:00

abstract：BACKGROUND:Cancer relapses may be useful to predict the risk of death. To take into account relapse information, the Landmark approach is popular. As an alternative, we propose the joint frailty model for a recurrent event and a terminal event to derive dynamic predictions of the risk of death. METHODS:The proposed pr...

journal_title：BMC medical research methodology

authors： Mauguen A,Rachet B,Mathoulin-Pélissier S,Lawrence GM,Siesling S,MacGrogan G,Laurent A,Rondeau V

更新日期：2015-04-01 00:00:00

abstract：BACKGROUND:Cluster randomised trials with unequal sized clusters often have lower precision than with clusters of equal size. To allow for this, sample sizes are inflated by a modified version of the design effect for clustering. These inflation factors are valid under the assumption that randomisation is stratified by...

journal_title：BMC medical research methodology

authors： Martin JT,Hemming K,Girling A

更新日期：2019-06-14 00:00:00

abstract：BACKGROUND:Most electronic search efforts directed at identifying primary studies for inclusion in systematic reviews rely on the optimal Boolean search features of search interfaces such as DIALOG and Ovid. Our objective is to test the ability of an Ultraseek search engine to rank MEDLINE records of the included studi...

journal_title：BMC medical research methodology

authors： Sampson M,Barrowman NJ,Moher D,Clifford TJ,Platt RW,Morrison A,Klassen TP,Zhang L

更新日期：2006-02-24 00:00:00