00:01
Hello students, one example of a mechanism that could lead to selection bias is health studies that recruit participants directly from clinic miss all the cases who don't attend the clinic or seek care during the study.
00:18
Due to this the sample and the target population may differ in significant way limiting your ability to generalize your finding.
00:25
Next, one example of mechanism that could lead to non -differential classification is when a medical record in which none of the health care worker remember to ask about tobacco use means these workers are working to record how many of the population is using tobacco but they themselves do not have their record.
00:49
This could be due to the forgetfulness or social desirability bias.
00:55
This will lead to non -differential misclassification.
01:00
Next, one example of a classification that could lead to differential misclassification is when mother of children with birth defect are likely to remember drugs they took during pregnancy differently than mothers of normal child.
01:15
In this case, subjects with disease may remember past exposure differently more or less accurately than those who do not have the disease.
01:25
Next, the loss to follow -up can lead to bias if the participants who are lost to follow up differ systematically from those who remains in studies...