Reach does matter, but not to the extent that a lot of media sellers make it sound, and not for the reasons that a lot of media buyers think. Here's why.

In last couple of months, I've been in a number of meetings with ad network representatives. If you haven't noticed, there are quite a few of them continually popping up. In particular, networks representing video inventory. They are legion, for they are many.

But the pitch for an online video ad network is not dramatically different from that of a standard online advertising network -- only quality sites, some black box technology that distinguishes how the ads are served and/or optimized, and reach that encroaches on the vastness of space.

The question I have for any of these online video ad networks, or any online ad network, or any online property that touts the size of its audience as a reason to buy it, is how does the size of your audience actually translate into reach for my advertising campaign?

What do they mean when they say reach?
We all think we know what reach is, but a surprising number of people asked to sell reach as a benefit of their network or website don't have a real understanding of what reach is. This isn't their fault, really, it's Nielsen's. When Nielsen started metering web traffic, it labeled the size of an audience visiting a given website over a set period of time (30 days has become the norm) as reach. Other research companies followed suit, and so then did the online publishing community.

However, reach as a metric in advertising doesn't refer to the size of a media vehicle's audience, but the percentage of a target audience that will have contact with that vehicle.

A crude count of a website or ad network's audience isn't good enough for establishing reach because it doesn't distinguish between the right people and the wrong people. Reach against a discrete audience is "reach," not a sum of that audience.

When that ad network's representative uses the word "reach" to describe the size of its audience, what they really mean is what used to be called "universe." Or, to keep it all straight, just "audience."

What ad networks and other online publishers -- and Nielsen and comScore -- really mean when they use the term reach is "potential cumulative reach." What that means is if you were to buy every impression served on every page for a month, you would attain the amount of reach that the ad network or site currently calls reach.

Can actual reach be determined?
Reach can be estimated quite accurately for schedules of web vehicles. Atlas DMT once had a product that attempted to give estimated campaign schedule reach, but it went away. Whether it was lack of interest, or it was too complicated to maintain, I can't say. But I did use it a lot when it was available, and there isn't really anything out there to replace it.

Currently, if you want to estimate pre facto for your campaign reach, you have to do it long-hand like you would against an unaudited magazine: take the target audience composition of the site and multiply it by the percentage of total site impressions you're buying. This gives you a pretty sad result, and it's only at a one-time frequency. It doesn't account for specific pages on a site being referenced by discrete audiences, for instance. But it is a place to start. 

The real challenge is solving the conceptual and technical problems that prohibit reliable estimates being made for schedules that mix both traditional media and internet vehicles.

Traditional, online and emerging media is becoming essential for advertising campaigns, and a better understanding of cross-media usage and the relative impact of messages from different sources have got to be had.

Does reach matter?
Reach does matter, but not to the extent that a lot of media sellers make it sound, and not for the reasons that a lot of media buyers think.

Reach matters, really, for one thing: scale. Most products and services rely on scale to make a business. Sure, if I'm selling Lamborghinis, I don't need to sell a lot of them. I can be extraordinarily direct with my marketing communications. I can take the time and effort to talk to that ONE person who is going to buy. But gum, soft drinks, canned foods, travel products, paper goods, etc.? I need to talk to a lot of people. The reach of my ad campaign is important because that is what it represents: scale.

However, for online, since the way reach is being used is really in reference to a potential cume, reach of an online advertising vehicle doesn't matter all that much unless I'm prepared to spend the money necessary to own the impressions that are going to affect that reach. And most advertisers I know don't like to spend in that way on a website. 

So, the next time you hear someone talk about the reach of their ad network or website, know that the reach they are talking about isn't the reach you need to know about, and it isn't the reach that your client cares about.

Media strategies editor Jim Meskauskas is vice president and director of online media for ICON International, Inc., an Omnicom Company.