Nielsen Norman Group finds by experiment that a "casual, conversational and enthusiastic" Web-site voice leads to favorable perceptions on the part of users of a brand's "friendliness, trustworthiness and desirability".

Testing was done using fake Web sites in the insurance, health care, banking and home-security industries.

Findings of interest:

• Of the 3 dimensions of favorability, trustworthiness was key.
• A conversational tone is well received when it comes from a "serious" industry, but a playful tone is not.
• Humor proved to be extremely risky.
• Quantitative measures of favorability are unreliable.
• Best approach is to ask users prompting but vague questions in order to elicit useful qualitative data about how they perceive your Web site.