QuestionThe District Health Officer is concerned that the number of reported cases seems low. To better characterize the population with polio in Ababa, the District Health Officer went to the hospital to review the charts of all children admitted with polio during the past two years. To his surprise, he found more cases with a discharge diagnosis of polio from the hospital in 1989 and 1990 than were reported from the whole district during the same years. Recall that in Ababa the working surveillance case definition for polio was the acute onset of flaccid paralysis plus fever. In reviewing the records, the Health Officer found that the data on signs and symptoms of children given the diagnosis of polio were not uniformly recorded. The District Health Officer sees this as an opportunity to design a new disease report form and uses this revised form for a new review. This hospital review identified a total of 143 cases of polio in 1989 and 1990.Table 2. Distribution of Polio Cases by Month and Year of Diagnosis after hospital record review: Ababa District Hospital, 1989 and 1990Month19891990Month19891990January1012July21February811August23March78September45April67October46May33November810June23December810The regional District Health Officers were interest in comparing rates in their regions. It was noted that the crude cumulative incidence in the Abbado District is 2x higher than the incidence rate is observed in the neighboring district of Lazu, but exactly the same as the crude cumulative incidence in another neighboring district of Hanna.Question 6: Aside from a true difference in incidence rates, provide and explain at least two possible reasons for the difference in incidence rates between Abbado and Lazu. What is one explanation that could be corrected for statistically, and how could this be accomplished? (10 points)MathStatistics and Probability PUBHLTH 630
