The three major ethnic/cultural groups are currently almost one-third of total population ( see AMIC's Abbott Wool's Market Segment Resource Locator ): African American is 13%, Hispanic is 12% and Asian American is 4%. The rule of thumb is always "consider" ethnic and cultural groups. There are several common or basic product categories in which these groups have a 150 - 300+ index of usage versus the remainder of population. These include fruit juice, baby products, rice, corn meal, and many brands of beer, popular foods or over-the-counter pharmceuticals.
General advertising doesn't reach the linguistically isolated portions of these markets (50% or more of Hispanics and various Asian national groups). Even those reached, among all the ethnic/cultural segments, are less impacted due to lack of appropriate cultural cues in the general advertising or the media environments.
Upon due consideration, the planner may find that for his or her particular advertiser, no special effort is required. But, the planners may also find that there is a 12% segment of their universe consuming 25% of their product, and reachable through efficient media. It is not really unusual for the "first mover" in one of these market segments to gain 10% market share among the segments, which equates to a gain of more than 1% national share, something that couldn't have been achieved for three times the budget in general advertising.
Non-ethnic segmetns such as the mature market may also bear consideration.
Telmar's media software includes a Spanish TV reach and frequency system, called STRETCH, created by Telemundo
Hispanic Broadcasting System (formerly Heftel) has created En Total which does general Hispanic radio calculations and media combinations.
The African American, Spanish, and Asian-American media all offer research analyses.