RESUMEN
Abstract Five compounds were isolated from the peels of chufa (Eleocharis dulcis (Burm.f.) Trin. ex Hensch., Cyperaceae). The chemical structures were determined by various spectroscopic analysis methods, including 1D and 2D NMR, and by comparison with literature data. All compounds were isolated for the first time from the peels of chufa. Compounds orcinol glucoside, leonuriside A, 2-hydroxymethyl-6-(5-hydroxy-2-methyl-phenoxy-methyl)-tetra-hydro-pyran-3,4,5-triol, and 1,4-dihydroxy-3-methoxy-phenyl-4-O-β-D-glucopyranoside showed good acrylamide formation activity, and acrylamide inhibition rates were 30.24, 32.81, 30.53, and 28.18%, respectively.
RESUMEN
Standardized means, commonly used in observational studies in epidemiology to adjust for potential confounders, are equal to inverse probability weighted means with inverse weights equal to the empirical propensity scores. More refined standardization corresponds with empirical propensity scores computed under more flexible models. Unnecessary standardization induces efficiency loss. However, according to the theory of inverse probability weighted estimation, propensity scores estimated under more flexible models induce improvement in the precision of inverse probability weighted means. This apparent contradiction is clarified by explicitly stating the assumptions under which the improvement in precision is attained.