Question

What direction of bias would weaken a conclusion that there was no
association between exposure and outcome?
Choose the single best answer: “toward the null”, “away from the null”, or
“cannot determine from the given information”.

Answer 1

In the research study, the bias generally occur when the variables like exposure and outcome are not measured correctly. The bias can be classified into two categories-

*Differential misclassification: This bias mostly occurs when there is significant difference between the amounts of misclassification between the variables exposure and outcome. In this case, the bias direction cannot be predicted.

*Non-differential misclassification: This bias generally occurs when there is no difference between the amounts of misclassification between the variables exposure and outcome. In this case, the variables is of dichotomous nature, that is, subjects might be exposed or unexposed towards the health outcome. In other words, exposed and unexposed subjects shares equal amount of misclassification towards health outcome that will might cause bias towards the null.

In hypothesis testing, the null hypothesis can be stated as there was no association between exposure and outcome which is the result of non-differential misclassification. So, in that case, the direction of bias that will weaken the conclusion is towards the null.

Hence, the correct answer is towards the null.