Bias and Validity

Question 1

Internal Validity

Answer 1

the extent to which the observed results represent the truth in the population that is being studied and is not due to bias, confounding, or random error

Question 2

External Validity

Answer 2

the extend to which the results of a study can be generelized to other contexts outside of the study population

if a study lacks internal validity, then external validity is irrelevant

Question 3

Random Error

Answer 3

errors due to chance that do not have a system effect on the whole sample and typically do not affect the estimates

Question 4

Systematic Error

Answer 4

error with a recognizable source (bias, confounding) that affects the estimates in a study

Question 5

Bias

Answer 5

a systematic error that results in an incorrect or invalid estimate of the measures of association/frequency

leads to appearance of an association when there is none or obscures an association that really exists

Question 6

What form of bias is most common and present in all types of studies?

Answer 6

information/misclassification bias

Question 7

Selection bias

Answer 7

bias in the selection of sample population

has to do with WHO gets in your study

animals enrolled in the study are different from the source population

Question 8

In what studies is selection bias more likely?

Answer 8

case-control – both outcomes and exposures have occured by the time the study subjects are selected