Question

Differentiate between bias and confounding. discuss the criteria necessary to establish a factor as a confounder and provide an example applying these criteria. what is one way to adjust for a confounding relationship in the study design or the analyst.

Answer 1

• Bias is defined as an error that creates deviation and results in incorrect estimation of the actual effect in an event.Biases may arise due to the fault in research method,sampling error or problematic concept of research.Confounding is a type of bias that occurs as a result of distorted outcome in a research.This can be due to an extranous variable, when correlated with the exposure causes this distortion.
• The necessary criteria for a confounder is: (a) the factor must be unequally distributed among the comparing groups.(b) there must be an association between the outcome and the risk factor. Ex: Consider that Birth order and Down syndrome are correlated to each other; Down syndrome is also related to the maternal age. See following illustration:
• 

• 
• The study design may be modified to either control or exclude the variables.Randomization is one of the ways to be applied for a strict control.This allows the study groups to attempt on a larger extent to even out any unk own confounders.Restriction is another way for keeping confounder out of the context.

Good Luck!