Well I learned something: there IS a rule of thumb for frequency and
effectiveness. But before I get to that, let me draw your attention to
a web page that contains thoughts on the subject from 1885, when the
consumer society and advertising were still in their infancy.
Hammer it home through repetition, Mr. Smith says. I doubt he used
sophisticated data collection to reach his conclusion, but nonetheless
he hit upon a truth and principle of advertising effectivess that
still stand today.
As it turns out, there is also empirical evidence for the role of
frequency in advertising recall and effectiveness. It is something
called the Ebbinghaus Retention Curve.
"After some number of repetitions, Ebbinghaus would attempt to recall
the items on the list. It turned out that his ability to recall the
items improved as the number of repetitions went up, rapidly at first
and then more slowly, until finally the list was mastered. This was
the world's first learning curve."
Note the implication that advertisers may overspend by going beyond
the point at which repetition has no further effect on recall.
Now for that "rule." I found it at a site that you may be find
especially useful, assuming (I probably should have asked) that you
are the owner of a small business and are planning to advertise. It is
the website of the National Federation of Independent Business.
Here's what they have to say:
"When designing and placing ads, many small business owners search for
the magic bullet: an ad that is so compelling that customers will
immediately pick up the phone and call to make an appointment.
The reality is, however, that advertising is a process, not a one-time
event. Advertising research has shown that a consumer usually needs to
see an ad five to seven times before responding. This is what the ad
industry calls the rule of seven.
Following are ways to incorporate the rule of seven into your
It ought to be well worth your while to read the rest of this web page.
Finally, some other sites I thought you might find of interest.
One is an interesting case history in which a decision to put more
money into frequency and less into space (ad size) led to greater
The other site, an academic paper, concentrates on frequency in online
advertsing and the special problems posed by an environment in which
"clutter" takes on new meaning.
This next site illustrates how extremely sophisticated and complex
media planning and buying can become when a big advertiser is spending
big bucks across many media, including "new media." (Also shows why
media planners earn big bucks!)
Finally, some words of wisdom on frequency in online advertising from
the folks at Ogilvy.
They recommend capping frequency at a level determined by their
"mFrequency" tool to be sufficient...and beyond which level money will
be wasted. (We can be sure that "mFrequency" is proprietary and
I enjoyed looking into this question for you, and I hope all this is
interesting and useful to you.
All the best,