Scenario #4 Consider a hypothetical investigation of an occupational exposure to an organic solvent that occurred 20 years ago in a factory. Over the years there were suspicions that working with the solvent led to leukemia, but no definitive data existed. Eventually, a retrospective cohort study was conducted using the employee health records. If all records had been retained the results would look like those shown in Table 4. Table 4: Results of Study RR=2.0 Leukemia No leukemia Total Exposed to solvent 100 900 1000 Unexposed 50 950 1000 Total 150 1850 2000 Suppose that many of the old records had been lost or discarded, but given the suspicions about the effects of the solvent, the records of employees who had worked with the solvents and got sick were more likely to be retained. Consequently, record retention was 99% among workers who were exposed and developed health problems, but recorded retention was only 80% for all other workers. 18. Would you be concerned about biased results in this situation? A. Yes, because this would result in differential bias B. Yes, because this would result in non-differential bias C. No, this would not likely result in bias