Identifying and Improving Validity

The following are examples of misclassification. Select all that apply:

• Differential

• Non-differential

• Prevalence-incidence bias

• Healthy worker effect

In non-differential misclassification the frequency of errors is approximately the same in the groups being compared.

• True

• False

Misclassification may only occur in cohort studies.

• True

• False

Differential misclassification is:

• Bias towards the null

• Bias away from the null

• Bias towards or away from the null

• No bias at all

Differential misclassification is caused by:

• Questionnaire bias

• Recall bias

• Prevalence-incidence bias

• Interviewer bias

Sampling bias is best avoided when using random sampling techniques.

• True

• False

Bias that results from errors in measurement, data collection, or interpretation of the exposure, outcome or both.

• Selection bias

• Information/Observation bias

• Prevalence-Incidence bias

• Attrition bias

Which is true about Berkon’s Bias?

• • Tends to cause the odds ratio to be overestimated

• General population based controls are more likely to encounter exposure then the hospital based control

• Hospital based controls are more likely to encounter the exposure then the general population

• None of the above

Neyman's bias occurs when...

• individuals with more severe or mild forms of the outcome are excluded from the study

• individuals with more severe or mild forms of the outcomes are included in the study

• individuals with minimal to no forms of the outcomes are included in the study

• All of the above

Which of the following statements are true regarding the Healthy Worker Effect?

• Occurs in case control studies when workers represent the exposed group and a sample from the general population represents the unexposed group

• • Occurs in cohort studies when workers represent from the exposed group and a sample from the general population represents the unexposed group

• • Seen in studies of occupational exposures

• Both B and C

• Both A and C