This article is the first of six that will provide the traditional marketer with a frame of reference and working knowledge of media mix as it applies to the online medium. This series should also be useful for the traditional media person and as a brush up for the Interactive planner or buyer.

This first article will set up a frame of reference, including discussion of terminology, resources, allocation, planning vs. buying and tracking and optimization. Many of these topics will be dealt with in depth in future articles.

It's hard to leap into a new area without at least some grasp of the language. There are a several good sources for detailed terminology. Among the best are a) ARF's Glossary of Digital Media Research Terms and b) MarketingTerms.com.

The first audience-related term to be used was "hit". This term is still used today but mostly incorrectly. A hit is a record in a common (Unix) log file. Many people use this term to indicate a visit to a site. A visit is a single session on a site, comprised of as many pages as the visitor views. In most cases, each element on a page (text, each graphic, each ad) represents a "hit". As such, a single visit will have many hits included. Since there is no relationship to hits and audience, we won't be revisiting this term.

Visitors are sometimes characterized as unique visitors. This is equivalent to the traditional media term "exclusive cume". While the term visitors counts every visit to a site, the term "unique visitors" counts each person only once and does not credit repeat visits.

The standard for measurement of traffic to Web sites is defined by two sources, Nielsen NetRatings and comScore's Media Metrix. Both sources have a significant share of market in the audience measurement arena. They provide measures of visitors, unique visitors, demographics and other data. Keep in mind that unlike other media, these ratings services can only measure site characteristics and, as of this date, are unable to measure advertising audience. This is key as the Internet is the only medium where the content audience and the advertising audience are not of the same magnitude. We accept that we lose some audience in TV through attentiveness or leaving the room and that not all magazine readers peruse every page. But at least the opportunity to see the ad is there and the drop off is probably only 10-20%. A single ad on MSN, unless there is a roadblock or page takeover specifically engineered to preempt all other advertising, will only reach a portion of the audience at any given time as other pages on the site will be serving ads from other advertisers at the same time. Please note that the use of the term "reach" by these companies refers to site reach or "cume potential". This should NOT be confused with the reach of your campaign as measured through traditional media. Only the third party ad servers can do that (see below).

Individual site visitor counts can be verified by I/PRO, the standard in site audits. Individual site demographics (like a subscriber study) can be measured by Tacoda.

A pageview represents a visit to a single page in a session. While many in the Internet marketplace equate the term pageview to advertising, the relationship is not one to one. It is possible to have a page without any advertising or to have a page that is abandoned before an ad is served. As such, when a site talks about pageview, they are describing their total advertising inventory available, not their audience size.

As with all traditional media, an impression is ideally characterized as an OTS, or opportunity to see the ad. Thus, similar to other media, an impression is a single exposure of a unique audience member (user) to an advertising unit. While the MRC, IAB, AAAA's ARF and others have worked to "normalize" this definition, for technical reasons having to do with ad serving, there remain several points at which an impression can be served. While there are many discussions of this on the Web, the curious reader is probably best served by reading the IAB information on this topic. For all practical purposes, most media buys assume no difference site to site, and in fact, it is expected that any differences will be resolved in the short term. As with other media, an impression may also be referred to as an exposure. Some also call it an adview.

Third party ad serving: Ads generally come from a different server than content. The server the ad comes from needs to control inventory and be able to pick out and serve the next appropriate ad, based on site parameters. It might literally be the next ad in the queue, but if registration or some other data point indicates demographic or sociographic aspects of a visitor, the ad server can also skip down through ads until it finds the most appropriate ad for, say an 18-34 year old female or one that the advertiser has targeted to those who have indicated an interest in travel.

Given the way that the Web and the Internet are constructed, the ad server can actually be anywhere in the world. Thus was born the concept of the third party ad server (3PAS). Companies like DoubleClick, Atlas DMT, Bluestreak, MediaPlex, 24/7 Real Media and others are employed by both publishers, advertisers and agencies to serve their specific advertising. Instead of the ad being embedded on the page, a tag is placed there by the site pointing to the server containing the assets (ads) that are to be served. The advantages of third party ad serving for the marketer are many, but include: a) the ability to make certain that all creative units are deployed at the same time, b) an assurance that all metrics (impression and post impression related) are on the same basis, c) an ability to go to one source and see up to date performance of a campaign at any time, and d) the ability to change advertising, either in part or on a wholesale basis, quickly.

As the 3PAS companies serve all of the impressions for an advertiser campaign, they become the source for counting the total audience for the campaign, not only on a gross impressions basis but on a net or unique basis (reach). The issue here is that the 3PAS do not measure demographics. This resulted in work done over the past several years to unify 3PAS information with ratings service demographic data in order to provide accurate reach and frequency estimates comparable to traditional media and which can be combined with traditional media for purposes.

Reach, the number of users exposed to a specified campaign or ad in a specified time period has been an elusive definition for the reasons outlined above. However, there is considerable work being done within the industry on this topic and credible first models have been released by companies like IMS, Telmar and Atlas DMT. You can also access R/F data through DoubleClick's Media Visor or from NetRatings and comScore directly. While the R/F development today only covers pre-buy or planning estimates, the tools are adequate for estimating the reach and frequency of a campaign with a variety of demographic possibilities. Within Telmar and IMS, this data can also be combined with other media R/F data for purposes.

Clickthrough is a commonly referred to metric. It represents the action of a user when they click on an ad or link and are transferred from the site they are currently viewing to a new location, usually the advertiser's site. More and more today, the branding effect is taking place and those exposed to advertising are coming to sites after the exposure has taken place. This is referred to as post impression or viewthrough. This can take place minutes, hours, days or weeks after the initial ad impression.

Through the use of cookies, a track record kept on an individual user's computer recording items like passwords and visits to sites, advertisers can determine if a visitor to a site has been exposed to an ad previously, enabling credit of a view through. Post advertising activity for many campaigns is split 50/50 between click through and view through today.

The result of back end tracking is that evaluation of Interactive campaigns can go far beyond the traditional CPM, or cost per thousand impressions metric. We can of course measure cost-per-click, or CPC. This metric however has become outmoded with more sophisticated metrics made possible through use of the 3PAS companies who track both clickthroughs and viewthroughs. The result is that an advertiser can now measure CPR: Cost per response, CPA: Cost per Acquisition (customer), CPS: Cost per sale, CPL: Cost Per Lead, CPO: Cost per Order, CPT: Cost Per Transaction or what has been called CPW: Cost per whatever (i.e., any of the above and more). If you can devote a page to and action on your Web site, it can be tracked.

The above data has put significant pressure on the Web to produce meaningful ROI (Return on Investment). Three factors enter the calculation. The cost of the media and advertising creative that contributed the sales in question is the denominator. The dollar value of those sales, minus costs, over the time interval assumed for the advertising's effects on sales (short, medium or long term) is the numerator. This calculation produces the dollar contribution to earnings for each media dollar spent.

In addition to the DR aspects of the Web, significant evidence of branding capabilities have been defined. There are many examples within MSN Advertising and other sites of branding efficacy on the Web. One of the great aspects of the Web is that, in addition to being a media vehicle, it can be a feedback loop. Companies like Dynamic Logic and Millward Brown Intelliquest have the capability to do the type of attitude, usage and awareness research on an almost instantaneous basis that historically has taken months to field and months more to collate results. Costs for this type of research on the Web can also be significantly lower than traditional AU&A research.

In future articles, we will discuss concepts like the allocation of Interactive budgets within the overall mix, planning vs. buying, tracking and optimization and other issues relative to .

David L. Smith is President and CEO of Mediasmith, Inc.		Karen T. McFee is Executive Vice President of Mediasmith, Inc.