The document outlines a presentation analyzing a dataset of egg counts from fish sampled along coastlines in England, France, and Ireland. It describes building Poisson and zero-inflated Poisson (ZIP) regression models to predict egg counts from variables like sampling time, sea currents, depth, and temperature. The ZIP model was found to have better predictive performance and model validation criteria than the Poisson model based on measures like AIC and MSE. The analysis aims to build a predictive model for egg counts that could be useful for fisheries management in other regions like Ireland and Spain.

1. Francesco Donelli
Giuseppe Giadone
Alessandro Esposito
Francesco Esposito

2. Outline of
the
presentation
Our dataset and goal of the analysis
Nature of the data and Poisson model
Zeros inflation and ZIP model
Model selection and predictive power
Final considerations

3. Goal of the analysis and content of the
dataset
v Goal: finding a good model with respect to both predictive power and model validation
criteria.
v Content: records about the number of eggs fished through the coasts of England, France and
Ireland.
v Variables:
• Egg count: number of eggs fished [response variable];
• Time: recording time;
• Flow: power of sea currents;
• C.dist: distance from sample to 200m contour (degrees);
• Salinity;
• S.depth: sampling start depth;
• Temp.surf: sea temperature;
• Net area: sampling net area.

4. Why remove latitude and longitude?

5. vCOLLINEARITY TEST OF THE
VARIABLES

6. Poisson model

7. vSUMMARY OF THE POISSON MODEL

8. vRESIDUALS vs FITTED

9. • Check for Leverages • Check for Outliers • Check for Influential Points

10. vHOW MANY ZERO?

11. Hurdle or ZIP?

12. ZIP Model

13. vSUMMARY OF THE ZIP MODEL

14. v VALUE OF AIC WITH ALL VALUES OF
FLOW

15. vVALUE OF MSE WITH ALL VALUES OF
FLOW

16. vEFFECTS OF FLOW

17. vNEW SUMMARY OF THE MODEL

18. Final conclusions (ZIP model)

19. vWHO NEEDS OUR MODEL?
Egg count

20. vEGG COUNT PREDICTED FOR
IRLAND AND SPAIN

21. THANKS FOR
ATTENTION

22. vAPPENDIX
Vuong test (zip is model 1)

23. Ocount: actual zeros
Pcount: predicted zeros

24. • Python code used to
implement the maps

25. Python code used to
create graphics in Final
conclusion slides

26. Poisson model residuals

27. ZIP model residuals vs fitted

28. Hurdle model