extra features of the telephone : a factor with levels
games, internet (which means games and internet) and
camera (which means games and internet and camera)
network
a factor with levels KPNVodaphone and
other
sms
the cost of an sms in euros (0.17 or 0.23)
design
a factor with levels basic or trendy
Source
Sandor Zsolt and Philip Hans Franses (2009) “Consumer price
evaluations through choice experiments”, Journal of Applied
Econometrics, 24, 517–535.