<正>Dear Editor:Medical education is associated with significant costs[1].Those who are responsible for the delivery of medical education must continually make decisions that have financial consequences[2].Sometimes decisions are to invest in a new product or service,sometimes to disinvest.Sometimes decisions involve the educator realising that they should switch from one provider of medical education to another,or from one product to another.Consciously or unconsciously these decisions are inevitably made on value-educators want to maximise the outcomes from medical education or to minimise costs[3,4].But decisions to change