It's hard to measure the effect of advertising when your subject is on the move, underground! Measuring how we react to advertising in the laboratory or the home (where we are watching TV or maybe our mobile phone) is hard enough. Try to adequately measure the effectiveness of advertising whilst in rush hour, frantically on the move and deep in a tunnel on the London underground and you will see the challenge we had on our hands.
This could also be of interest:
Authors: James F. Shaw, Robert M. Worcester
June 15, 1973