They are technically competent and thus convincing.

Expert power

$2.$ They have prescreened, evaluated, and synthesized product information in an unbiased way

Legitimate power

$3.$ They tend to be socially active and highly interconnected in their communities. They are likely to hold offices in community groups and clubs and to be active outside of the home.

Knowledge power

$4.$ They tend to be similar to the consumer in terms of their values and beliefs