8-3. Selective Survival

1. What is meant by "bias due to selective survival" in cross-sectional studies? (In your answer, make sure to define appropriate selection probability parameters.)
2. Under what circumstances might there be no selective survival bias even if the selection probabilities are not all equal?
3. Suppose that you could assess that the direction of possible selective survival bias in your study was towards the null. If your study data yielded a non-statistically significant odds ratio of 1.04, would it be correct to conclude that there was no exposure-disease association in your source population? Explain.