Stratification allows to control for confounding by creating two or more categories or subgroups in which the confounding variable either does not vary or does not vary very much. The Mantel-Haenszel formula is applied in cohort and in case-control studies to calculate an overall, unconfounded, effect estimate of a given exposure for a specific outcome by combining stratum-specific relative ris...

The present study evaluated genetic diversity of Lithuanian populations Lythrum salicaria in relation to parameters riparian environment. Growing along Nemunas, Seaside and Lielupė river basins, 15 were examined using amplified fragment length polymorphism markers. Molecular data related the type land use cover, natural vice versa regulated fragments rivers. Population mean as follows: percenta...

Mantel N, McPherson K, Peto J, Smith PG: Design and analysis of randomized clinical trials requiring prolonged observation of each patient.

This study aims to explore psychometric characteristics and detect whether the teacher-made chemistry learning evaluation instrument contains item bias that can benefit students of a certain gender. The research sample was 358 class XII SMA in Yogyakarta who were taken by cluster random sampling then answer analyzed Winsteps Rasch Software 3.73. In general, it be concluded achievement is good t...