Contents
What are baseline variables?
A baseline covariate is usually defined as a qualitative factor or a quantitative variable measured or observed before a subject starts taking study medication (usually before randomisation) and expected to influence the primary variable to be analysed.
What is baseline comparison?
The Baseline Comparison Report displays a side-by-side comparison of items and relationships in two baselines. This report is like the Baseline Compared to Current report, but instead compares two specific states of selected items at a certain point in time.
How to adjust for differences at baseline in controlled trials?
A better approach to adjust for differences at baseline is to use an analysis of covariance (ANCOVA) which, in spite of its name, is a type of regression. In an analysis of covariance, follow up scores are plotted against baseline scores and parallel straight lines (linear regression) are fitted through the scores for treatment and control
What happens when you adjust for baseline values?
However, adjusting for baseline values by including them in our model will increase the precision of our estimated treatment effect, even when there aren’t baseline differences ( Senn, 2019 ).
How are change scores used to account for difference at baseline?
Change scores are often used to account for differences between groups at baseline. However, they do not control for baseline imbalances between groups. This is because subjects with low scores at baseline tend to improve more than those with high scores, a phenomenon known as regression to the mean.
How is covariance adjusted for differences at baseline?
An analysis of covariance adjusts each subject’s score for their baseline score and is unaffected by chance baseline differences and regression to the mean. This method is easily applied to data at two time points, and assumes linearity between baseline and follow up scores where data are continuous.