Contacts in a shrunken world. K.W. Axhausen and A. Frei. Great circle distance (km) Face to face [%] Great circle distance [km]

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1 Face to face [%] Great circle distance [km] Phone [% Great circle distance [km] [%] Great circle distance [km] SMS [%] Great circle distance [km] Great circle distance (km) 1'000 10'000 Contacts in a shrunken world K.W. Axhausen and A. Frei Arbeitsbericht Verkehrs- und Raumplanung 440 March 2008

2 Contacts in a shrunken world March 2008 Arbeitsbericht Verkehrs- und Raumplanung Kontakte in einer geschrumpften Welt KW Axhausen IVT ETH CH 8093 Zürich A Frei IVT ETH CH 8093 Zürich Telefon: Telefax: axhausen@ivt.baug.ethz.ch Telefon: Telefax: frei@ivt.baug.ethz.ch March 2008 Kurzfassung Auf der Grundlage einer neuen grossen Zürcher Befragung zur Art und Häufigkeit des Kontaktes zwischen den Befragten und ihren sozialen Kontakten schätzt dieser Aufsatz die notwendigen Strukturmodelle, um Aussagen über die relative Wirkung der möglichen Einflussgrössen zu ermöglichen. Die SURE Regressionsmodelle der Häufigkeiten und die Logit-Modelle der Marktanteile der Besuche, Anrufe, nachrichten und SMS zeigen, dass ein exponentieller Entfernungseffekt beide Prozesse dominiert. Unter den anderen Variablen spielen nur die Dauer des Kontakts, die Fussläufigkeit der Distanz, Alter, Einkommen und die Anzahl der bisherigen Umzüge eine grössere Rolle. Die Analyse der Distanzen und der sich ergebenden sozialen Netzwerkgeographien erfolgt in einem zweiten parallelen Aufsatz. Schlagworte Soziale Netze, Anzahl der Kontakte, Art der Kontakte Zitierungsvorschlag Axhausen, K.W. und A. Frei (2008) Contacts in a shrunken world, paper presented at the 86 th Annual Meeting of the Transportation Research Board, Washington, D.C., January

3 Contacts in a shrunken world March 2008 Working paper Contacts in a shrunken world K.W. Axhausen IVT ETH CH 8093 Zürich Telephone: Telefax: axhausen@ivt.baug.ethz.ch A. Frei IVT ETH CH 8093 Zürich Telephone: Telefax: frei@ivt.baug.ethz.ch March 2008 Abstract Based on a substantial new Swiss survey of personal networks, this paper analyses the impact of precisely-measured geographical distance on the frequency and market shares of different modes of interaction between the respondents and their contacts (face-to-face, phone, and SMS texting). Geographical distance influences how people interact today, as it did in the past. The effort involved in the different modes of contact (face-to-face, phone, and SMS) qualitatively matches the strength of the distance decay in the frequency of those interactions. The patterns of the market shares follow this differential distance decay. The frequency of faceto-face visits and their market shares fall quickest with distance. While frequency is unaffected by distance, its market share rises fastest with it. The reverse is true for SMS messaging, which stays stable in terms of market share, while only slowly falling with distance in terms of frequency. The high starting frequency of phoning translates into growing market shares, even if its absolute frequency falls with distance. Keywords Social network, mode and frequency of contact, face-to-face, , SMS, phone, modal share, distance, geography Preferred citation style Axhausen, K.W. and A. Frei (2008) Contacts in a shrunken world, paper presented at the 86 th Annual Meeting of the Transportation Research Board, Washington, D.C., January

4 Contacts in a shrunken world March Maintaining contact in a shrunken world The 2004 official UK tourism statistics 1 report that 37% of all non-regular travel 2 was motivated by visits to friends and relatives (VFR). A share of 59% was reported for South Africa (Rule, Viljoen, Zama, Struwig, Langa, and Bouare 2003). The 1995 American Travel Survey classified 33% 3 of the reported journeys as VFR, but a further 33% involved purposes which people rarely or never engage in alone, such as outdoor sports (e.g., golf, sailing) or family events (e.g., weddings, funerals), so that the true share of long-distance journeys which are fully or partly motivated by the wish to see families and friends is even higher. The numbers are 29% for VFR and 34% for other pleasure/leisure activities in the 2001 US National Household Survey 4,5. In Switzerland, a 23% share was reported for VFR in The share of VFR journeys seems to have increased since the late 1980s: at that time the share was 21% in the UK, 23% in Australia and 34% in Zaire (Jackson 2003 citing 1988 World Tourism Organisation statistics). The patterns of these journeys cannot be understood without understanding how social networks of relatives and friends are distributed over space. Shares of 40% of daily travel and 40% of daily mileage travelled for leisure are also common in industrialized countries (e.g., Bundesamt für Statistik 2000 or Bureau of Transportation Statistics 1995). Again, daily leisure travel is mostly about being with other people, members of one s own household or with social contacts. The social capital embedded in these networks finds expression in these journeys and the associated communication via mail, , phone calls, SMS messages, electronic chats, and video or picture websites. The impact of these journeys in terms of energy consumption and emissions, which is expected to increase further with the continuing globalisation of production and labour, forces transport policy and travel behaviour analysis to engage with the mechanisms through which travellers build and maintain social capital and social networks. Otherwise, transport policy is bound to optimise its instru The World Tourism Organisation defines tourism as travel beyond the range of daily life, generally involving an overnight stay away from home. 3 Own analysis based on the data available at 4 Own calculations based on table 1 in BTS (2003), correcting for the commuting included in the table. 5 Calculations based on daily travel reveal shares of 25% and 32%; courtesy of Heather Contrino, FHWA, Washington, D.C. 6 Private communication with Prof. Lässer (University of St. Gallen) 3

5 ments blindly, looking only at its own metrics, overlooking the impact on the social capital structure of society. Our current knowledge of the physical distances between the members of a social network and the dependence of the patterns of interaction on distance is surprisingly limited (see below for a brief review). This paper and its companion paper (Size and structure of social network geographies, Frei and Axhausen 2007) contribute to this understanding. Based on the largest survey to our knowledge to address this issue in detail so far (see below for a description), this paper will analyse the frequency of interaction between the respondents and their contacts in their personal networks and will model the shares of the different modes of communication (face-to-face, phone, , SMS). The companion paper will focus on the number of contacts reported, their distances and the resulting social network geography. Unease about changes in the spatial patterns of social network membership has been a topos in the literature since at least the 1970s (for references see Campbell 1990; Campbell and Lee, 1992; Day 2006 or Lloyd 1984). Changes in accessibility have permitted travellers and residents to adjust the geography of their daily lives and their social networks (see also Hampton and Wellman 2003). While Friedman (2005) speaks of a flat world, it is more appropriate to think of it as a shrunken world (see Dicken 1998). Since 1950, public investment in motorways and roads and private investment in vehicles have scaled Switzerland down for the road user by a factor of two (Figure 1). The comparable factor is for Swiss public transport (Axhausen, Fröhlich, and Tschopp, forthcoming). Car ownership and operating costs have fallen even faster (see Frei 2005; Raff and Tratjenberg 1995). The collapse of long-distance telecommunication costs over the same period has been even more dramatic. Figure 2 shows the US experience as an example, but note that this time series ends before the widespread adoption of internet services, and now the associated adoption of zero-marginal-cost voiceover-internet-protocol (VOIP) telephony. Note also how the mobile phone has reduced efforts to find and access a phone. Since World War II the joint effect of price and travel time reductions and frequency increases in air travel has been on the same order of magnitude as telecommunication changes. The regionalisation process of air services, bringing lower access and egress costs and times, and the adoption of low-cost airline business models is not yet complete, especially in Europe or Asia and for intercontinental flights. This promises further reductions in generalised costs 7. 7 The generalised cost of a trip is the weighted sum of resources consumed, i.e. time and money as perceived by the traveller given the comfort, reliability and safety involved. 4

6 The analyses could be improved technically. Given the nature of the frequency estimates, it would be safer to treat the frequencies as categorical variables and employ a multivariate, ordered probit approach for the analysis (see Scott and Kanaroglou 2002). As some modes are not chosen in certain relationships, the analysis could adopt suitable discrete-continuous modelling approaches, such as the one proposed by Bhat (2005). The logit model employed here does not allow for the possible heteroscedacity of the errors, nor did it account for the repeated measure nature of the underlying data of up to 48 observations for one respondent. Greene, 2002, suggests appropriate approaches. Finally, these results need to be integrated into the wider discussion about the structure of and trends in the social capital of our societies (Seligman 2000; Putnam, Feldstein, and Cohen 2003; Raje, Grieco, Hine, and Preston 2004). Will the maintenance of private social capital, so powerfully demonstrated here, sufficiently balance the externalities of the localised anomie generated by residents who are too frequently away with friends from beyond the neighbourhood (Axhausen 2006, 2007)? 7 Acknowledgements The work reported here was made possible by the generous and gratefully acknowledged support of the Institut für Mobilitätsforschung, Berlin and the Swiss Bundesamt für Bildung und Wirtschaft as part of the COST Action Literature Axhausen, K.W. (2006) Social factors in future travel: A qualitative assessment, IEE Proceedings Intelligent Transport Systems, 153 (2) Axhausen, K.W. (2007) Activity spaces, biographies, social networks and their welfare gains and externalities: Some hypotheses and empirical results, Mobilities, 2 (1) Axhausen, K.W. (2007) Predicting response rate: A natural experiment, Arbeitsberichte Verkehrs- und Raumplanung, 434, IVT, ETH Zürich, Zürich. Axhausen, K.W., A. Frei and T. Ohnmacht (2006) Networks, biographies and travel: First empirical and methodological results, paper presented at the 11th International Conference on Travel Behaviour Research, Kyoto, August Axhausen, K.W., C. Dolci, P. Fröhlich, M. Scherer and A. Carosio (2006) Constructing timescaled maps: Switzerland 1950 to 2000, Arbeitsberichte Verkehr und Raumplanung, 342, IVT, ETH Zürich, Zürich. 25

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