repeat is easy for consumer packaged goods (usually, a repeat purchase), but it really means the trial was successful - the buying unit was pleased. for onetime purchases (industrial or consumer ) , we have to decide what statistic will tell us that. some people use the direct one: "were you satisfied?" sometimes an indirect one - such as "have you had occasion to recommend the product to others?" - is better. in the case of the cellular picturephone - camera , buying a second unit would