Search results for "Cochran–Mantel–Haenszel statistics"

2019

Background and Purpose— Prevalence of atrial fibrillation (AF) is increasing, but the impact on overall burden of stroke is uncertain, as is the proportion that could be attributed to under anticoagulation. We did a population-based study of AF-associated stroke and a systematic review of time trends in other stroke incidence studies and of rates of premorbid anticoagulation. Methods— The proportion of incident strokes with associated AF was determined in the OXVASC (Oxford Vascular Study; 2002–2017) and in other prospective, population-based stroke incidence studies published before December 2017. Proportions were pooled by Mantel Haenszel methods, and the pooled percentage of cases with …

Utility of the Mantel-Haenszel Procedure for Detecting Differential Item Functioning in Small Samples

2004

Sample-size restrictions limit the contingency table approaches based on asymptotic distributions, such as the Mantel-Haenszel (MH) procedure, for detecting differential item functioning (DIF) in many practical applications. Within this framework, the present study investigated the power and Type I error performance of empirical and inferential criteria for DIF detection in small samples. Sample sizes (50/50, 100/50, 200/50, and 100/100 for the reference and focal groups, respectively), ability distributions (equal and unequal), and amount of DIF (moderate and high) were manipulated. The results show the advantages of employing theMHchi-square statistic using high levels of significance (•…

Liberal and Conservative Differential Item Functioning Detection Using Mantel-Haenszel and SIBTEST: Implications for Type I and Type II Error Rates

2004

The aim of this work was to determine, in terms of Type I and Type II error rates, the risks of applying various statistical procedures for evaluating differential item functioning. To this end, the authors carried out a simulation study in which the Mantel-Haenszel and SIBTEST procedures were applied in conjunction. The variables manipulated were sample size and distribution of ability between groups. Results indicated that, although there was a high rate of agreement between the procedures, the joint Type I and Type II error rate may vary substantially from that obtained when each of the procedures was applied separately. Furthermore, the authors analyzed empirical data to obtain informat…

Discriminant ability for caries risk of modified colorimetric tests.

2010

Objetive: The aim of this study was to evaluate the relationship between the caries risk in children over a two-year period and their baseline caries status, salivary levels of mutans streptococci and lactobacilli, and results of the Alban test and modifications thereof using different substrates. Study design: Ninety-five children aged 6-7 were examined in Granada (southern Spain) for dental caries at baseline and every six months. Stimulated saliva was sampled and inoculated in 7 colorimetric tests based on Snyder's medium with different sugars and polyalcohols. A mutans streptococci and lactobacilli count was performed (Dentocult SM strip® and Dentocult LB®). Caries risk proportions were…