Frequency

Counting only the times an ad appeared on a screen makes two very different situations look identical. One million people seeing it once and a hundred thousand people seeing it ten times both come to one million.

That played out at Pagedeck the month Ravi doubled the ad budget. Appearances doubled and signups barely moved. Checking the number of people reached, it was within 10 percent of the previous month. The extra budget had gone into showing the ad again to the same people rather than finding new ones.

Frequency turns that distinction into one number. Divide impressions by reach and you get how many times, on average, one person saw it.

Divide impressions over a fixed period by reach over the same period. Four things get decided.

1. Pin the period down first. Measured weekly a campaign reads 1.5; the same campaign measured monthly reads 6, because a longer window gives one person more chances to see it again. Report the window with the number every time.
2. Pull both inputs from the same period. The times an ad appeared on screen are impressions; the number of people who saw it is reach. A month with 1.2 million impressions and 200,000 reach gives a frequency of 6.
3. Don't stop at the campaign average — break it out per creative. An average of 6 often hides one creative at 14 and another at 2. Decisions about what to switch off come from the broken-out numbers.
4. Account for device and platform boundaries. One person who saw it on a phone and a laptop counts as two, which reads lower than reality.

The number is neither good nor bad on its own. Repeated exposure to the same people eventually leads into ad fatigue, where response falls off, so read the rising frequency alongside the falling click rate.

"Impressions doubled and reach didn't move. Frequency went from 3 to 6."

A diagnosis that the budget didn't go toward new people.

"This creative is at 14. If the same people have seen it fourteen times, it's better switched off."

Judged on the per-creative number rather than the average.

"Monthly it's 6 and weekly it's 1.5. Let's agree on the basis before we quote it."

A value without its period stated can't be compared.

The month Ravi doubled the budget, the number had gone from 3 to 5.5. Broken out per creative, one of them sat at 14 and its click rate had halved.

Ravi switched that creative off and moved the budget toward widening the targeting to grow reach. The next month frequency came down to 4 and signups rose again.