example question from the EpiStats
Brian Lee presents to the clinic with recurrent epigastric pain that occurs about two hours after eating. He attributes the pain to the stress associated with going to high school. After obtaining the relevant information from the history and physical examination, Dr. Turner suspects a helicobacter pylori infection and counsels her patient that ordering a stool antigen assay would be appropriate. Mr. Lee gives consent, but admits that he is a little confused about something. What he would like to know is why people sometimes sat that a negative test is a good thing. Dr. Turn explains that if an investigation is very sensitive, then a negative test simply means that the patient probably does not have the condition. In a hypothetical study, 252 out of 304 positive tests and 322 out of 368 negative tests were correct. Based on this information, what proportion of people with a helicobacter pylori infection would Dr. Turner tell her patient are correctly identified by the test?