Stratification ensures that the numbers of participants receiving each intervention are closely balanced within each stratum.
After propensity-score matching, patient distributions were closely balanced between the high-dose methylprednisolone and the control groups.
Some other phenotypes are also balanced by each other: Th17 cells, induced by IL-6, IL-1β and TGF-β, are closely balanced by regulatory T cells (induced by TGFβ only) [ 5].
Block randomisation using random block size will be utilised, and stratification will be performed to ensure that the numbers of participants receiving each intervention are closely balanced within each Australian State.
The trial arms were closely balanced in sample size in the parent trial cohort (telehealth=49.7% (1605/3230), usual care=50.3% (1625/3230)) but showed a marked discrepancy in the questionnaire study's complete case cohort (telehealth=56.8% (431/759), usual care=43.2% (328/759)).
They suggested that while each are likely to be important to women, current estimates about their rates meant that harms and benefits were closely balanced; in this situation, qualitative differences between the two made it impossible for experts to draw exact conclusions about where and when equipoise arose.
Such a characteristic would have to be largely independent of the characteristics that were closely balanced between our study cohorts in order to have produced this effect, and the numerous variables that were part of the propensity score make this unlikely.
Stratified randomisation is achieved by performing a separate randomisation procedure within each of two or more strata of participants (eg, categories of age or baseline disease severity), ensuring that the numbers of participants receiving each intervention are closely balanced within each stratum.
Study findings might have been influenced by the considerable diagnostic heterogeneity of this patient cohort, although each individual diagnosis was closely balanced in prevalence among lithium and valproate recipients and almost 90% of our sample had mood disorder diagnoses (Additional file 1: Appendix 1).
The delegates to next weekend's conference were elected as part of a separate ballot held in December last year and are understood to be more closely balanced between the party's left and right.
