In the instrumental-variable models, however, there is no straightforward way to add the imputation error to the variance estimator allowing the computation of correct standard errors.
RBC transfusion was included as a variable in multivariable models; however, the number of transfused patients was too low to provide solid data on the effect of RBC transfusion on outcome parameters.
The usage pattern that included progestin use 15 25 days per month was modelled as a separate variable in statistical models; however, the number of cases was small and the effect estimates were consistent with sequential and continuous regimens and are not reported.
For example, the variable year was found to be a very important variable in all of the models; however this variable would not be applicable in a prospective analysis.
Variable-air-volume models, however, automatically decrease airflow when the sash is fully closed, reducing the energy consumed by ventilation.
It was possible to include a large number of potential confounding variables in the statistical models; however, it is possible that a key unknown confounding factor during early life was omitted, which might explain the differences observed in MS outcome between the mode of delivery groups.
No variables were excluded from entry into the models; however, for some variables that we had previously categorized (age, BMI, and Charlson Index), we now entered them into the models as continuous variables.
For descriptive purposes, continuous variables are shown as quartiles in table 2. In all regression models, however, these variables were used in their original form.
The associations which were sent to us and the associations performed by us have not undergone peer review (e.g. for variable selection when adjusting the models), however we have included this information in our review and the statistical technique used to remain as transparent as possible.
To compensate somewhat for this limitation, the use of psychiatric medications was included in the models; however, these variables exhibited no significant effect on outcome.
Third, we extracted the data with the largest number of adjusted covariates in the multivariate statistical models; however, other unmeasured variables may also exist.
