To control for possible confounding variables
, we conducted linear multiple regression analyses.
Possible confounding variables
such as pre-procedural administration of anticoagulation, anti-platelet therapy, and waiting time before sheath removal were described, but whether there was a significant difference observed among the groups on these variables was not explained in the study.
Then, multiple logistic regression was used to adjust for potential confounding variables
, ie, the model included the independent variables of mode of delivery plus all confounding variables
and the dependent variable of back pain.
The findings also confirmed that real-world associations between music lessons and intelligence cannot be attributed solely to potential confounding variables
such as parents' education or family income.
were minimized to more clearly define the role of both the number of rib fractures and patient age in determining outcome.
The authors are careful in each of their investigations to control for confounding variables
Analysts examined maternal and neonatal medical outcomes and use of resources; they calculated risk differences, adjusted for potentially confounding variables
, to assess the statistical significance of apparent disparities between the groups.
There are too many confounding variables
which have to be taken in to account by each individual woman or man.
These anthropometric and lifestyle variables were then regressed on serum ferritin concentration with potential confounding variables
using direct multiple linear regression.
One 3-hour course in research and program evaluation, a typical counselor education program offering in line with accreditation standards (Council for Accreditation of Counseling and Related Educational Programs, 2001), is not sufficient to prepare school counselors to conduct sophisticated evaluation studies, which necessarily have numerous confounding variables
and "noise" in a school setting.
The lack of efforts to study context, recommended by some authorities on evaluation research design (National Science Foundation, 1997; Patton, 1990), were particularly problematic because of potential confounding variables
that were not addressed methodologically in the Hutchinson study.
Most studies that have attempted to estimate OSAS mortality have been criticized for their small sample sizes, short followup, failure to control for confounding variables
associated with obesity or smoking, and other shortcomings inherent in retrospective natural history studies.