A data frame with 10 observations on the following 4 variables.
treeid
a numeric vector needed for identifying a tree in the MPT algorithm
sex
a numeric vector taking the value 1 if male and 0 if female
resp
a factor denoting the transport mode choice, where D denotes driving one's own vehicle, F denotes getting a ride with a friend, O denotes other, P denotes using public transport, and W denotes walking
fr
a numeric vector recording the frequency with which each transport mode is chosen
References
United States Department of Health and Human Services and National Institute of Health and National Institute on Drug Abuse (2010). Drug Abuse Treatment Outcome Study, 1991-1994. Ann Arbor, MI: Inter-university Consortium for Political and Social Research.