1. Poisson Regression with Rates
Traffic Deaths in Finland on Friday the 13th and Other Fridays
Simo Näyhä (2002). “Traffic Deaths and Superstion on Friday the 13th,” American Journal of Psychiatry, Vol. 159, #12, pp

2. Data
Traffic Deaths and Exposure by Gender on Friday the 13th and Other Fridays in Finland for years
Traffic Deaths are Given as Counts by Friday type and gender
Exposure is person days (100,000s)

3. Poisson Model for Rates

4. Likelihood and ML Estimates - I

5. Likelihood and ML Estimates - II

6. Friday the 13th Results – Regression Coefficients

7. Predicted Values, Residuals, Risk Ratios

8. Friday the 13th Results TDR=Traffic Death Rate (per 100,000 exposed)
Males tend to have higher accident death rates than females. The Friday the 13th effect is not significant for males (Risk Ratio interval contains 1). The Friday the 13th Effect is significant for females (Risk Ratio interval is entirely above one)