The phrase "a separate stratum" is correct and usable in written English.
It can be used in contexts discussing layers, levels, or categories, often in fields like geology, sociology, or data analysis.
Example: "In the study of social dynamics, we must consider a separate stratum of the population that has different needs and behaviors."
Alternatives: "an independent layer" or "a distinct level".
Methods and Results One hundred ninety-three patients with symptomatic PSVT were enrolled in 4 double-blind, randomized, placebo-controlled clinical trials with almost identical trial design (supraventricular arrhythmia-1 [SVA-1], SVA-2, SVA-3, and SVA-4), performed as a separate stratum of studies that also included a stratum of patients with atrial fibrillation or flutter.
The model treated each clinic as a separate stratum when calculating standard errors for the estimates.
The patients constituted a separate stratum of a larger trial, the Stockholm Adjuvant Tamoxifen Trial.
Estimates of conditional logistic regression were generated using the PhReg procedure with each case forming a separate stratum.
The stratified Cox regression includes a separate stratum for each woman; thus, each woman has her own baseline rate function.
The meta-analysis of genotypic risks over all studies was also conducted using logistic regression, treating each study as a separate stratum.
In a country as complex as this, in which tourists have for so long existed in a separate strata to locals, the only way to learn anything about the "real Cuba" is to talk.
We looked at smokers as a separate strata (data not shown) and found several differences with non-smokers.
A test for heterogeneity between the trials is not significant (P = 0.07) if the NSABP study in situ lesions are taken as a separate strata, and only marginally significant (P = 0.04) if they are excluded.
Anti-HCV+ PHIV did not show an increased NHL risk compared to anti-HCV− PHIV in any separate stratum except for HIV transmission category, where a significant association between anti-HCV and NHL risk emerged among MSM (OR=2.37; 95% CI: 1.03 5.43).
The term R = diag(V 1, … V H ) represents the error structure, which is assumed to be a diagonal matrix with separate stratum variances, represented by V h where h indexes strata and H is the total number of strata.
