A commonly used model for the relationship between advertising awareness and weight of advertising is that of Simon Broadbent, One way TV advertisements work. In the paper Short-term modelling of advertising effectiveness: A confirmation of Broadbent’s Model (Jex), it was found that from the very general class of Box-Jenkins Transfer Function models the Broadbent type model was indicated as being the most appropriate for National Griobank data. The present paper extends this work to cover the possibility that the parameters of the Broadbent model may change in time. Discount Weighted Estimation has been used to track parameter changes. These changes may be slow, due to decay of effectiveness or ‘ageing’ of a campaign, or they may be sudden, due for example to competitor activity.
