During a recent appearance on Maggs on Media, I stated that the most important foundation for any outdoor media effectiveness is to look at the medium in terms of 'narrow-casting'. After a barrage of emails asking for an explanation, here is how I see it.
"Broadcast" media such as TV, digital, radio and print deliver your message, creative and copy almost uniformly, and that's why they can work with 'one size fits all' readership/audience and demographic matrices per publication or program.
Assuming you choose to engage with it, "Beep Bank's" radio commercial will be delivered to you in your car the exact same way as to the person sitting in an office in Boksburg. This would apply to the fragrance advert on page 15 of a glossy magazine for the reader in Centurion and the reader in Nelspruit.
However, "narrow-cast" media such as billboards does not benefit from the same effect. Again, assuming the viewer has chosen to engage with your board in Durban, there are many factors relating to the board that can make its impact superior or inferior to another of the exact same size, format and creative in Cape Town.
Visibility time affects my ability to absorb your creative, as do elevation, surrounding visual clutter, obstructions and so on. So how useful is a traffic count, even if it has been broken down in demographics, if there is visual pollution, or the board is partially obstructed where your contact number is displayed?
Each board "narrow-casts" within the environment it sits in. Thus traffic count and demographics are only part of the 'impact matrix' which should be layered onto each board's wider rating that takes into account the other issues mentioned above.
Brand managers and agencies need to regularly review these ratings as factors such as road construction, foliage causing obstructions and stolen materials that can defeat your reach and frequency plan.
Sometimes though, the change works in favour of the advertiser. An example of this is Continental Outdoor's board on Maunde St. in Atteridgeville (major arterial into and from Pretoria Central) that started off having a left and right side, but is now in the centre as they turn the road into a dual carriageway. FNB and MTN, the advertisers on both sides, immediately benefit from better visibility from both directions.