The following is a guest blog post from Bob Gramer, founder of media buying and advertising consulting company Multiple Media Consultants.

When playing the numbers games in media analysis, there are two things we are always concerned about…reach and frequency.

The goal is to reach as many target potential customers with enough frequency to make sure the message is received and understood. With radio, frequency becomes even more important since we are working with only the sense of hearing in a limited span of time.

Those with limited budgets may have to sacrifice some reach in order to optimize their schedules with adequate frequency. Media gurus and consultants do not always agree on what the optimum number is when talking about frequency in radio. Most will agree that somewhere between a 3 and 5 weekly frequency will produce the best results. That is not to say that you will run 3 to 5 ads per week. It means that you will run enough ads during the week (within a given daypart) to reach a determined number of potential listeners and average of 3 (up to 5) times each.

Given budget limitations, it may be better to reduce the number of stations and/or day-parts in order to get an adequate frequency. In a small to medium sized market, your optimum schedule may be to spend $ 2,000.00, reach 15% of your demographic target, with a 3.5 frequency. If you had $ 5,000.00 to spend, your goal would be to add a station or two, maintain a 3 to 4 frequency, and increase your reach to 25-30%. This would be optimum for the budget you have to work with.

Sophisticated media buyers have the tools to provide this information to their clients. Retailers and buyers placing their own schedules may have more difficulty in determining reach and frequency.

Here is a formula to help determine how many ads it takes (within a daypart) to accomplish a frequency goal:

1. Daypart Quarter Hour (divided by) Daypart cume = X
2. Desired frequency (divided by) X = number of ads to schedule within the daypart.

While this formula does not consider duplication, reach, effective reach, or cost efficiency, it does give you a rudimentary way to make sure you have an adequate frequency to optimize your radio buy from the frequency perspective.

• *Average Quarter Hour (AQH): Number of target listeners in a 15-minute segment of the broadcast daypart.
• **Weekly Cumulative Audience (cume): total potential number of target listeners on a station…within the broadcast daypart.
• Daypart, quarter-hour, and cume numbers can be provided by your local media rep.