Measuring Activity Spaces and Social Networks: Methodology and Results

1. Preferred citation style for this presentation • Frei, A. (2006) Measuring activity spaces, social networks geographies and biographies: some methodological and empirical results, presentation at the COST 355 – WG3 meeting, Prague, October 2006.

2. Measuring activity spaces, social networks geographies and biographies: some methodological and empirical results A Frei IVT ETH Zürich October 2006

3. Trends: Road travel time scaled Switzerland (1950 & 2000) Scherer, 2004

4. Trends: Quality controlled prices of the mean new Swiss car Frei, 2005

5. Trends: Real price of telecommunication Adapted from FCC (2001)

6. Measures • Requirements: • Low dimensional (scalar) • Describe size, orientation and spread • Consistency with behavioural possibilities (theoretical intent) • Ease of calculation

7. How to measure ? • Parametric: • 95% confidence ellipse (form and type of distribution) • Semiparametric: • Inclusion geometries (form of geometry) • (Weighted) shortest path networks (structure of path) • (Percentage) Minimum convex poligons (convexity) • Kernel density estimator (form of estimator)

8. Measures: Confidence ellipse Schönfelder, 2006

9. Measures: Minimum convex polygons (MCP) • MCP Percentage MCP Schönfelder, 2006

10. Measures: Kernel densities Schönfelder, 2006

11. Measures: Shortest path network Schönfelder, 2006

12. Measures: Weighted shortest path network Schönfelder, 2006

13. Measures: Inclusion geometries • Find: • min Ai(i1 .....  in) • s.t. • Area Ai covering p% of all observed points • with: • i : Type of geometry (Ellipse, bean, Cassini ...) • p : Predetermined share, e.g. 95%

14. Measures: Inclusion geometries

15. How do we explain travel and what is missing ? • Distribution of activities • Distribution of land use patterns • Generalised costs on the available infrastructure • Budget constraints • Capability constraints

16. Number of accompanying travellers (2003 Thurgau)

17. Items to capture the social network geographies • Name generators • Name interpreters • Type and length of contact • Frequency by mode of contact • Home location • Second homes • Detailed descriptions of face-to-face contacts

18. Items to characterise the mobility biography • Home and second home locations • Work and school locations • Household composition • Mobility tools • Main mode (to work/school) • (Major holidays) • Personal income • Household income

19. Data available – Name generator and interpreter • ifmo: • “Persons with whom you had contact” • (f-to-f frequency, location, mobility biography) • DfT: • Family, non-local friends, most important persons • (location, frequency by mode, mobility biography) • COST 355: • Important people, people with leisure contacts • (location, frequency by mode, mobility biography)

20. Biography of an architect

21. 18 to 39 years 40 to 59 years 60 years and more Residential mobility

22. Contacts

23. Poisson regression of the number of social contacts

24. Distance distribution

25. Contact frequency by mode

26. Market share by contact mode

27. Example geography of a 35 old female

28. Distribution of the social geographies Germany: 357; U.S.A: 9’629 [103 km2]

29. Tobit regression of the Ln (social geographies)

30. Assessment: Measuring activity spaces • Wide-ranging distributed places can be measured with the confidence ellipse • The symmetry of this measurement leads to too big spaces • Inclusion geometries can relief the symmetry problem

31. Results from the initial models • Biography has an impact on the number of contacts given • Strong distance decay of contact frequency • Strong distance effects on contact mode share • Biography affects the size of network geography

32. Questions?

33. Literatur • Axhausen, K.W. (2005) Activity spaces, biographies, social networks and their welfare gains and externalities: Some hypothesis and empirical results, PROCESSUS Colloquium, Toronto, June 2005. • Carosio, A., C. Dolci and M. Scherer (2005) Erreichbarkeitsveränderungen in der Schweiz: Eine kartographische Darstellung, in K.W. Axhausen and L. Hurni (eds.) Zeitkarten Schweiz 1950-2000, Chapter 3, IVT and IKA, ETH Zürich, Zürich. • FCC (2001) Long distance telecommunication industry, FCC, Washington, D.C. • Frei, A. (2005) Was hätte man 1960 für einen Sharan bezahlt?, MSc thesis, IVT, ETH Zürich, Zürich.

34. Probit results

35. Items to capture social content • Detailed purpose coding • Social purpose and obligations fulfilled with it • Beneficiaries of the activity • Composition of the party • Prior locations • Distribution of the travel and activity costs • Planning horizon • Number of previous visits to that location • Secondary activities

36. Zürich experiment

37. Response burden and response rate