There are several techniques that businesses have found to be useful indicators and effective measures of the value of a particular advertising approach.

• Track which directories in the market area are increasing the number of yellow pages and becoming more densely filled with paid advertising year after year.
• Ask the customers who call-in to recite the page number where they found your phone number. This is an automatic key to which directory is being used, and to which heading in the directories are most frequently used for your product type. (Telephone users tend to use the same directory time and again, but they can not always state reliably which telephone directory they are using.)
• Observe which directory is in plain view as you visit homes, businesses and offices, and which directory gets used in your own home.
• Ask women, who make a high percentage of the shopping decisions, which telephone directory they prefer.