Selection Bias, Cigarette Smoking and Dementia - Essay Example

The lack of a control experiment enhances the manifestation of the selection bias especially given the fact that some of the selected samples die.

In determining the credibility of the study, one must investigate the initial distribution with the view to determining the nature of the selection bias. Selection bias is a statistical error that affects the validity of the study. By analyzing the nature of the error as is in the study, it becomes easy to interpret the variables by manipulating other features of the study. Estimating the effects of unbiased treatment is yet another fundamental way of determining the credibility of the study. Such strategies as case matching, multivariate stratification, and covariance adjustments help observe consistencies in the research and thus validate the credibility of the research (Bostrom, 2002).

Indeed, the study had a selection bias of concern. The study graph shows that the groups scored four points higher on the pretest than the comparison group. Additionally, the group had an average of fifty-four while the comparison group had an average of fifty. Such is a manifestation of an error that requires effective treatment during interpretation. Read More