نتایج جستجو برای: matched case control studies
تعداد نتایج: 3744722 فیلتر نتایج به سال:
Background: Impacted tooth is common in dental practice. Dentists usually remove them if they are associated with any pathologic sign or symptom. The challenge is whether to extract the asymptomatic tooth or not. This study was conducted to determine the association between developmental odontogenic cysts and tumors and impacted and unerupted teeth, if left untreated. Methods: In ...
recently multiple studies have shown that elevated homocysteine levels may be associated with ophthalmic vascular disease. to investigate the role of high plasma levels of homocysteine in the patients with retinal vein occlusion, 21 patients with retinal vein occlusion (rvo) and 20 age and sex matched controls without rvo were included in this retrospective case–control study. information regar...
the present study was conducted to investigate the effect of implicit focus on form through input flooding and the effect of noticing, explicit focus on form on linguistic accuracy. to fulfill the purpose of the study, 86 iranian pre-intermediate efl learners of one of the language institutes were chosen by means of administering ket as the homogeneity test. these learners were pretested throug...
Background and aims: Despite substantial advances in the etiology of autism spectrum disorder (ASD),the environmental risk factors have not yet been well understood. The present study investigated theassociation between ASD, and maternal and perinatal risk factors.Methods: This matched, case-control study was conducted in Hamadan, the west of Iran, fromNovember 2015 to M...
the purpose of the present study is to find out whether bilinguals of khuzestan-arab origin or monolinguals of iranian origin code-switch during learning or speaking english and which group is more susceptible to code-switch. to this end, the students of 24 classes from high schools and pre- university centers were screened out, and interviewed and their voices and code-switchings were recorded...
It is tempting to assume that confounding bias is eliminated by choosing controls that are identical to the cases on the matched confounder(s). We used causal diagrams to explain why such matching not only fails to remove confounding bias, but also adds colliding bias, and why both types of bias are removed by conditioning on the matched confounder(s). As in some publications, we trace the logi...
We present a Bayesian approach to analyze matched "case-control" data with multiple disease states. The probability of disease development is described by a multinomial logistic regression model. The exposure distribution depends on the disease state and could vary across strata. In such a model, the number of stratum effect parameters grows in direct proportion to the sample size leading to in...
We examine the impact of nondifferential outcome misclassification on odds ratios estimated from pair-matched case-control studies and propose a Bayesian model to adjust these estimates for misclassification bias. The model relies on access to a validation subgroup with confirmed outcome status for all case-control pairs as well as prior knowledge about the positive and negative predictive valu...
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