EPI 202 Lab 1.docx - EPI 202 Lab 1 1 In a study of malnutrition and diarrhea in children under age five in Sudanese community 154 episodes of diarrhea

# EPI 202 Lab 1.docx - EPI 202 Lab 1 1 In a study of...

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EPI 202 Lab 1 1. In a study of malnutrition and diarrhea in children under age five in Sudanese community, 154 episodes of diarrhea were observed in 38.51 person-years of observing among children who were 75% or less the expected weight for their age, and 287 episodes of diarrhea were observed in 88.83 person-years of observation among children who were 90% or more of the expected weight for their age (EI Samani et al; Am J Epidemiol, 1988). a. Construct an appropriate table to describe the data, and calculate the incidence rates for each of the two groups. < 75% > 90% Case 154 287 441 Person Years 38.51 88.83 127.34 IR (PYs) 4.00 3.23 b. Test the hypothesis that there is no association between malnutrition and rate of diarrhea. Interpret the numeric results succinctly. H 0 : There is no association between diarrhea and expected weight less than 75%. (I 1 =I 0  I 1 -I 0 = 0  I 1 /I 0 = 1  ln(I 1 /I 0 ) = 0) HA: There is association between diarrhea and expected weight less than 75%. (I 1 ≠I 0  I 1 -I 0 ≠0  I 1 /I 0 ≠1  ln(I 1 /I 0 )≠0) Z 2 = [ X E ( X | H 0 ) ] 2 Var ( X | H 0 ) x 1 2 X = 154 T = ¿ 133.36 E ( X | H 0 ) = M 1 ×N 1 / ¿ ^ Var ( X | H 0 ) = M 1 N 1 N 0 T 2 = 93.04 Z 2 = [ X E ( X | H 0 ) ] 2 Var ( X | H 0 ) = 426.0 93.04 = 4.57 Pr [ x 2 > 4.57 ] = 0.04 < 0.05 We reject the null hypothesis at the 0.05 level of significance.

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• Summer '14
• FrancisCook