The alternative hypothesis (HA):
Answer: a) Assumes there is an association between exposure and outcome
Explanation: The alternative hypothesis (HA) for chi square test assumes there is an association between exposure and outcome. The null and alternative hypothesis for chi-square test is:
H0: There is no association between exposure and outcome
HA: There is an association between exposure and outcome
The alternative hypothesis (HA): Assumes there is an association between exposure and outcome Assumes there is...
1. If the stratum specific relative risks show a similar association between exposure and disease and these are different from the crude association, then confounding is present. Group of answer choices True False 2. The ability to generalize the study results to a larger population is known as Group of answer choices internal validity external validity confounding 3. Exclusion bias is a form of Group of answer choices confounding information bias selection bias non-response bias
You have conducted a case-control study to determine the association between exposure to lead and development of cognitive disorders. Exposure data were collected from measuring blood samples and outcomes data from medical records. Participants were randomly selected to be included into the study. The investigator who obtained the exposures and outcomes data was blinded to the outcome status of the participant. In your study, you find an OR of 1.01. However, the actual association between exposure to lead and cognitive...
Question 41 What can be said about confounding if there is no association between the exposure and the potential confounder? There is a positive confounding effect There is a negative confounding effect There is no confounding The confounding effect is influenced by effect modification The confounding effect is biased Question 42Which of the following statements about confounding variable is TRUE? It is associated with either the exposure or the disease, but not both It is associated with the exposure, but not the disease It is associated with the disease, but...
Researchers are planning to conduct a case-control study of the association between an occupational exposure and a health outcome. The researchers plan to study exposed workers from one factory and compare them with unexposed retirees who have never worked in a factory. A reviewer of the research proposal is worried about selection bias and in particular about the possibility of the healthy worker effect. Which of the following best represents the reviewer's concern? a. Retirees should not be compared to...
1-Which of the following alternative explanations should be ruled in order to consider a study valid? a-Bias b-Confounding c-Random error d-All of the above 2-Which of the following defines confounding? a-An error committed by the investigator either in the design or conduct of study that leads to a false association between the exposure and disease b-A natural mixing of effects between an exposure, an outcome, and a third extraneous variable c-A result of false association between the exposure and disease...
True or False 1. If a study finds statistically significant association between exposure and disease, that must mean that every person who is exposed will get the disease. 2. A survey can be reliable but still not close to the true value. 3. Bias is random deviation of results from the truth. 4. Screening for disease is one type of secondary prevention. 5. In order for an infectious disease to occur, there must be a susceptible host.
True or False 1. If a study finds statistically significant association between exposure and disease, that must mean that every person who is exposed will get the disease. 2. A survey can be reliable but still not close to the true value. 3. Bias is random deviation of results from the truth. 4. Screening for disease is one type of secondary prevention. 5. In order for an infectious disease to occur, there must be a susceptible host.
11. In a cross-sectional study, the investigator measures the exposure and the outcome at the same time in a sample of individuals. The following data are from a hypothetical cross-sectional study that tested the hypothesis that persons who engage in recreational physical activity are less likely to have trouble sleeping. Trouble sleeping (% yes) Recreational physical activity: Yes 20% No 40% What conclusions can you draw from these results about the association between recreational physical activity and trouble sleeping? Please...
1. In testing hypotheses, the researcher initially assumes that the alternative hypothesis is true and uses the sample data to reject it. True False 2. The first step in testing a hypothesis is to establish a true null hypothesis and a false alternative hypothesis. True False 6. The power curve provides the probability of Correctly accepting the null hypothesis Incorrectly accepting the null hypothesis Correctly rejecting the alternative hypothesis Correctly rejecting the null hypothesis 7. Suppose that Ho: μ ≤...
2. Which of the following statements is TRUE (1 mark)? a) Selection bias can be reduced by increasing sample size. b) Loss to follow-up in a cohort study can bias findings either towards the null (reducing the magnitude of the true association) or the opposite (over-estimating the magnitude of the true association). c) Systematic error can be reduced by taking repeated measurements. d) Non-differential misclassification of exposure or outcome usually biases study findings away from the null (towards finding an...