Advertising: The Star and Highveld 94.7 out-earn Sunday Times and Metro FM

"The Star carried the highest gross advertising investment for 2001 at R306 million compared to closest rival Sunday Times at R242 million," she says, "and on radio 94.7 pipped Metro Fm with advertising revenue of R134 million compared to R116 million. Figures are based on gross spend, that is, without taking discounts into consideration."

Her curiosity piqued, Bolton dug deeper: "There are any number of rational reasons for this, but it was worth exploring in terms of cross tabulating AdEx and AMPS data," she says.

The first step was to determine if there was a match between total size of audience and revenue or if there were other variables. By analysing total regular readers for newspapers, and a past seven day audience for radio and then ranking them by size, Bolton discovered that there is very little correlation between the ranking of the top revenue earners and the total audience. Beeld for example ranks 3rd in terms of revenue but only 8th in terms of total audience. In radio, 94.7 ranks 1st in revenue, but a lowly 8th in number of listeners.

Bolton examined other variables. "The options are numerous, and the list was by no means exhaustive, but a better correlation was achieved by considering the reach each newspaper had of adults living in Gauteng with a household income of greater than R7000 per month," she says. "The tables show clearly that The Star, Sunday Times, Beeld, and Rapport fall into the top four in terms of revenue and also in terms of their readership of Gauteng adults with a household income of R7000 or more."

On radio the better match for adspend earned by the stations was obtained by comparing against their reach of adults with a personal income of between R12 000 and R20 000 per month. The top five ad revenue generators were 94.7, Metro FM, East Coast Radio, Jacaranda and 5FM. These all ranked in the top five against adults with a personal income between R12 000 and R20 000.

"There is no doubting the evidence that earning capacity of an audience is a strong positive in determining where the ad rand is spent," says Bolton, "with possibly a preference for selected provinces bearing in mind that the Cape press came in at position 5 and 6 in terms of revenue. Perhaps those legendary blonde bimbo media buyers from Sandton aren’t so far off the mark after all."

All AdEx figures quoted above are net of self-promotion.