• by Tom Hespos , April 11, 2006

A question that seems to come up a lot about online ad campaign recommendations concerns the balance of composition and coverage. To be more precise, clients who often prioritize coverage over composition often wonder why online agencies tend toward the opposite approach.

Coverage is an important metric, but in online campaigns, coverage carries less weight, particularly in targeted campaigns.

Do a research run against almost any broad demographic audience. You'll find that the Big Three and many of the larger sites out there have huge coverage of your demographic target, but there will be a pile of sites that have much higher composition figures. Your inclination might be to first go after targeted areas on the high-reach portals. Often, that approach itself can lead to a reduction in your campaign's overall potential reach.

While it may be true that a portal can reach a huge percentage of a demographic target, it's important to remember that unless your syndicated research tool of choice breaks down audience statistics into channels or more targeted selections, you're getting a figure for the entire site. It would be impossible to achieve the reach figures quoted, unless you secured enough inventory to give you a dominant share of voice. Not only would this be costly, but it would be wasteful as well. You would likely be reaching too many people outside your demographic target for this to be cost-effective.

Hand-picking targeted content areas or using demographic targeting on high-reach sites can certainly help, but don't expect to be able to achieve the kind of reach figures syndicated research indicates. It is rare that a site will have targeting information for 100 percent of its audience (or even something close). By targeting, you're decreasing the potential reach of the campaign right out of the gate.

For these reasons, many online media planners opt to use targeted sites with high composition of the target before they go anywhere else. While it's true that media planning involves a healthy balance of composition and coverage, composition tends to matter more in online than it does in other media.

On a site with high composition, your untargeted (ROS, RON, etc.) impressions will go a lot further, and they'll generate less waste. True, you need to check to make sure that you don't overspend on sites to the point of excessive frequency, but you'll find that it might be more cost-effective to roll up five or six targeted sites than to cherry-pick inventory on a single portal.

With market conditions for online ad inventory the way they currently are, targeted inventory on larger sites is a lot harder to come by. When inventory demand is high, buying around high-priced, broad-reach sites with inventory from smaller, more targeted sites can help keep your costs down.