MNTRC Newsletter Vol. 21, Issue 2: Fall 2014

Do social networks influence transportation choices?


Michael Smart, Asst. Professor, and Nicholas Klein, Postdoctoral Researcher, Rutgers University

Grafitti-tagged MTI car

Do social groups in low-income neighborhoods affect travel choices?

Rutgers News – Transportation and urban planning scholars have frequently perceived car ownership as a binary state – either a household owns a car or it does not. However, current research underway at Rutgers University finds that households, particularly those who are economically marginalized, frequently transition into and out of car ownership.

The study’s goal is to determine whether living in particular neighborhoods with members of one’s own cultural group influences travel patterns. Those groups include immigrants, the elderly, and same-sex partnered households.

Poverty affects frequent car ownership changes

Initial findings suggest that many households transition between owning and not owning cars throughout the survey years. This is particularly true for households in poverty, immigrants to the US, and minorities. Families who are in poverty during all of the survey years are four times more likely to transition from owning a car to having none (or the other way around). Sixty-eight percent of these long-term poor households change auto-ownership status during the 11 years, compared with only 17 percent of households not in poverty.

The project uses longitudinal (observations of the same variables over time), geocoded data to help understand the increased propensity of these groups to use public transit in environments with dense social networks.

Study data goes back 15 years

For this analysis, the research team is using the confidential, geocoded version of the Panel Survey of Income Dynamics (PSID).* Current analysis relies on data from seven waves of survey data collected biannually from 1999 through 2011 including roughly 9,000 families and 22,000 individuals. However, the research team hopes eventually to include data as far back as 1968.

The team is drafting an “initial look” paper to analyze the volatility of car ownership over time among low-income and immigrant populations and racial and ethnic minorities. This paper makes use of the longitudinal nature of the PSID to explore these changes over time as various families’ economic and material circumstances change. The study will be submitted to the 2015 Annual Meeting of the Transportation Research Board.

* PSID is a national study of socioeconomics and health over lifetimes and across generations. Funded by the National Science Foundation, the study began in 1968 with a nationally representative sample of over 18,000 individuals living in 5,000 families in the US. Information on these individuals and their descendants has been collected continuously since then.