EPI 811 – Work Group Exercise #2

Team Honey BadgersAlex Montoye

Kellie MayfieldMichele Fritz

Anton Frattaroli

‘CSI’ output.

Exposed Cases are low birth weight infant deaths Unexposed Cases are normal birth weight infant deaths Exposed Non-cases are low birth weight infant survivors Unexposed Non-cases are normal birth weight infant survivors The “Risk” values are a measure of incidence The “Risk difference” is the attributable risk (for exposure) The “Risk Ratio” is the incidence in the exposed divided by the incidence in

the unexposed. The “Attr. Frac. Ex.” is the risk difference divided by the incidence in the

exposed. The “Attr. Frac. Pop.” is the proportion of the total risk attributed to the risk

difference between the total and unexposed groups. “56% of infant deaths in the population are attributable to low birth weight.”

The confidence intervals identify the probability of the actual value falling within that calculated range.

The chi^2 test statistic is a test of significance for a contingency table. The probability of theChi^2 statistic is actuallygreater than 0, but is displayed as equaling zero.

‘CSI’ output analysis.

‘iri’ Command

‘iri’ Command 2

‘iri’ Command Differences

The incidence rate difference has a sign change (the C.I. bounds are swapped as well)

The incidence rate ratio is the reciprocal of what it was before.

The Prev. Frac. Ex. is the same absolute value as the Att Frac Ex, however it signifies an opposite effect (preventing cases rather than causing cases).

The Prev. Frac. Pop. Is the complement of the proportion where the numerator is the number of person-years not attributable to the exposure while the denominator is the total person-years

•Data represents men over the age of 65 = 1 or 0 = under the age of 65 •IRR = incidence relative risk, the risk of males dying when exposed to trigeminal neuralgia compared to females•M-H Weight: adjusted odds ratios for age (calculated by the exact method)•Crude IRR: total men incidence rate over total women incidence rate•M-H combined: weighted average of IRR across strata•Test of homogeneity (M-H): M-H = Mantel-Haenszel tests for homogeneity, looking for a difference across strata•Chi2(1) is the significance level, Pr>Chi2=0.8992 is the calculated value• Death in men with trigeminal neuralgia is not significantly different

across age strata

‘ir’ Command & Annotations

‘Confidence Intervals’

•95% confidence interval: an estimated range of values in which the actual value will fall 95% of the time•90% confidence interval: an estimated range of values in which the actual value will fall 90% of the time

THE END!