Each medium -- newspaper, television, radio -- measures its audience differently. That makes comparative analysis a difficult challenge for everyone. Here's a glossary of common terms to help sort through the hype and the jargon.

ABC Audit: An independent auditing service that verifies circulation counts for newspapers and magazines.

AQH/Average Quarter Hour: A typical 15-minute period on radio.

Audience: Individuals who read a newspaper or magazine, or listen to a radio broadcast, or view a television broadcast.

Circulation: The number of households to which a newspaper is delivered plus the single-copy sales (street sales.) It is a measure of the number of physical units sold on a single day not the number of adults reading the publication.

CPP/Cost Per Point: The dollars spent per GRP. Calculated by dividing cost by the GRPs.

CPM/Cost Per Thousand: The cost per one thousand individuals (or homes) delivered by a medium or media schedule. The most important question to ask is: "Cost per thousand what?"

Cume: The cumulative unduplicated total audience over two or more time periods.

CUME EXAMPLES: Newspaper: The unduplicated number of adults who "read or looked into" the publication within a specific time frame. A Sunday/daily cume is the number of adults who read or looked into the publication on either day. If a person reads the paper on both days, the reader is counted only once. Radio: Usually measured as a weekly cume -- the unduplicated number of persons who tuned in at any time during the week during at least one 15-minute period 6 a.m. to midnight, Monday through Sunday. A weekly radio cume measures 504 time periods. TV: Often measured as weekly cume--the unduplicated number of persons who tuned in during any half-hour period from 6 a.m. to 2 a.m. Sunday through Saturday. A weekly TV cume measures 280 time periods.

Frequency: The total number of times an individual sees or hears an ad.

Gross Impressions: The total number of times an advertising message is seen or heard. People who see or hear an ad multiple times are counted multiple times.

GRPs: Gross rating points reflect the accumulated audience exposed. Individuals may be counted more than once. It's calculated by counting the gross impressions, dividing by the target population and multiplying by 100.

Reach: Net reach is the unduplicated number of people or households exposed to a medium, not to a specific advertisement.

Rating: The percentage of the targeted population that is tuned to a station or program.

Readership: The number of adults (18+) in a specified geographic area who "read or looked into" into the publication yesterday.

ROP or Run of Press: An ad that runs in all editions or zones of the newspaper.

Share: The percent of those with TVs or radios turned on who are viewing or listening to a specific program. It is not a percentage of the total population because it does not take into account those individuals who have their TVs or radios turned off.