1-Select the type of Bias: In a case-control study of the association between HPV vaccination and HPV infection, the investigators discovered after the study that the case group tended to over-report their HPV vaccination exposure. Under-reporting was not a problem in the control group
Selection bias Measurement bias (Observation bias)
Confounding
Sampling error
2-If the 95% CI includes the null value of 1.0, the effect measure is statistically significant.
True
False
3-Suppose that we undertake a cohort study to examine the association of high salt intake and hypertension. Our study population consists of male and female Hispanics and Caucasians. No matching or restriction is performed. Let’s assume that the following facts are true: Caucasians consume more salt than Hispanics. Irrespective of their salt consumption, Caucasians have a greater risk of developing hypertension. Smokers consume the same amount of salt as non-smokers. Smoking is an independent risk factor for hypertension. Men consume more salt than women. Irrespective of their salt consumption, men have the same risk of hypertension as women. Based on the above information, which of the following are likely confounders in this study?
Gender
Smoking
Race/ethnicity
None of them
4-An investigator conducts a study to determine the association between the number of hours spent studying and the risk of depression among graduate students. He determines that the risk ratio comparing students who study 15 or more hours per week to those who study 5 or less hours per week is 1.8 (95% CI 0.7 – 2.9). If, in reality, there actually is an association between the number of hours spent studying and the risk of depression, what type of error is present?
Type I error
Type II error
Type III error
Ecological fallacy
5-Which of the following statement is false?
Bias can be reduced by increasing the sample size
With selection bias, subjects have a different probability of being selected according to their exposures or outcomes of interest
Measurement bias may result in a Type II error
Biases can be partially or completely eliminated or minimized through rigorous study design





