The document discusses treating statistical models like pets that require individualized attention or like herds that can be modeled collectively. It notes some people treat computers like pets while others see them as herds. Statistical models can be treated as pets by performing actions like variable selection and assessing goodness of fit for individual models, while modeling herds focuses more on population-level modeling and data enrichment. However, subject data is often messy and complex, posing challenges for modeling many individuals versus modeling collectively in herds.

1. Models: pets and herds
Carlos J. Gil Bellosta
cgb@datanalytics.com
September 2014
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 1 / 21

2. This is a pet...
Source: http://jessfalcone.wordpress.com
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 2 / 21

3. ... and this is a herd
Source: http://bonfirehealth.com/negative-influences-comparisons-social-cues-herd/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 3 / 21

4. Some people treat computers as pets...
Source: aliexpress.com
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 4 / 21

5. ... an others like herds
Source: Failure Trends in a Large Disk Drive Population, Pinheiro et al.
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 5 / 21

6. This is a statistical model treated as a pet
Source: http://www.ats.ucla.edu/stat/stata/seminars/interaction_sem/interaction_sem.htm
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 6 / 21

7. Pets are very demanding and require...
1 variable selection,
2 checks for outilers,
3 assessment of the goodness of

8. t,
4

9. nding con

10. dence intervals,
5 calculating p-values,
6 interpretating the results,
7 discuss the generalization,
8 ...
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 7 / 21

11. Models... as herds?
Source: http://www.gotmedieval.com
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 8 / 21

12. Model construction: population
Source: http://timyeo.wordpress.com/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 9 / 21

13. Model construction: data enrichment (aka left join)
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 10 / 21

14. But subject data is often messy...
Source: http://arquitectolegista.com.ar/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 11 / 21

15. ... and contains temporal data...
Source: http://thirdorderscientist.org/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 12 / 21

16. ... that is dicult to

17. t in a box (table)
Source: http://cutestcatpics.com/cat-trying-to-fit-into-tiny-box/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 13 / 21

18. We have a whole dataset per subject!
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 14 / 21

19. ... and a model per subject?
Source: http://www.unc.edu/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 15 / 21

20. (Most) models are sophisticated summaries of data
Source: http://xkcd.r-forge.r-project.org/
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 16 / 21

21. Do you seek ? Build a model per stock!
Carlos J. Gil Bellosta { datanalytics Models: pets and herds September 2014 17 / 21