The CPM model is the standard billing method for online advertising across all professional media.  CPM, Cost Per Thousand (M stands for the roman numeral for thousand), is a way for newspapers and media outlets to monetize each ad impression (an impression is each instance an ad is shown in the browser) in an accurate and metered approach. 

This method both protects the publisher and the advertiser.  The publisher is able to assign a value for each time an ad is shown and the advertiser has the leverage to purchase a defined amount of exposure.

Flat Rates are All Wrong
Many organizations sell their online inventory on a flat rate basis (ex. $100 for a month).  This does no one any favors. 

Due to the seasonality of the traffic in college media (see image for reference), each month or week presents a different set of traffic.  For example, an advertiser who purchases a month-long campaign in January will receive an entirely different result than the advertiser who purchases a campaign in October – despite having paid the same amount. 

Likewise, college media is very susceptible to viral spikes in traffic due to the way news travels through the community.  Any one scandal or news item can break in a week, cause an abnormal spike in traffic and create huge amount of exposure for an advertiser that purchased that particular time period.  Whereas, if a set amount of impressions were purchased by that advertiser, the increased exposure would have a value and could drive up revenues.

Control Over Time
Moreover, selling online inventory by a CPM model provides more options in ad delivery for an advertiser.  A set number of impressions can be applied over a longer span of time for prolonged exposure; making a smaller buy last longer and freeing up inventory for an increased number of smaller buys.  Also, ads can be deployed at specific times of the day or night for maximum impact in order to reach the audience intended (students at night versus alumni and parents during the day). 

Exercising these options in combination with targeting ads to certain areas of the site can be more effective with your audience and bring return business to the online edition.

CPM in the Rate Card
The transition to this billing model can often be difficult for local advertisers to grasp.  The key is to first have sales staff comfortable in the terminology and process of an online campaign.  Then over the course of a few semesters, the rate card should reflect standard impression buys that are similar to the week or month long packages typically sold in the past. 

For example, (disclaimer: using round numbers for simplicity's sake) if a newspaper sold month-long campaigns for $100 and that typically yielded 10,000 impressions in the past, then listing a package for 10,000 impressions for $100 on the rate card the next semester is a intermediary step to a CPM model.   Calculate the effective CPM (eCPM) from this situation and raise the CPM based on demand the following semester.