1. Grading the FOB The Fecal Occult Blood (FOB) test is used to screen people for bowel cancer. As expected, if it comes up positive, then you are told you likely have bowel cancer. If it comes up negative, you are told you are likely okay. So the outcome is dichotomous: either a "thumbs up" or a "thumbs down." A study involving 203 people was designed to assess how well the FOB works. Two things were recorded for each participant in the study: whether the FOB said they had bowel cancer and whether they really did (as determined by an endoscopy). The results are in Table 8.9. a. How do you know from the table that there were 203 people in the study? c. What percentage of the time did the FOB make the wrong decision? i. About 9% of the time ii. About 1% of the time iii. About 49% of the time iv. About 41% of the time d. What might be the consequences of the FOB screening test saying "positive" when the patient really didn't have bowel can i. This would potentially create unnecessary anxiety for the p ii. There are no immediate consequences since not having bowel cancer is a very positive outcome. iii. A patient with a potentially fatal disease might be deprived of the quickest postscreening intervention possible. Iv. The patient would now be much more likely to also have a positive outcome on the gold standard treatment, thereby prolonging an unnecessary stay in the health care system. e. How often did the error of saying "positive" when the patient really didn't have bowel cancer occur? i. 18 times ii. 2 times Iil. 1 time iv. 182 times f. What might be the consequences of the FOB saying "negative" when the patient really did have bowel cancer? i. This would potentially create unnecessary anxiety for the patient. ii. There are no immediate consequences since not having bowel cancer is a very positive outcome. iii. A patient with a potentially fatal disease might be deprived of the quickest postscreening intervention possible. iv. The patient would now be much more likely to also have a positive outcome on the gold standard treatment, thereby prolonging an unnecessary stay in the health care system. g. How often did the error saying "negative" when the patient really did have bowel cancer occur? i. 18 times ii. 2 times iii. 1 time iv. 182 times h. Looking at your answers to parts e . ​
and g .
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is the FOB a good test or not? Defend your answer.