SAN JOSE, Calif. — Getting people to click on paid advertisements is crucial for Internet search companies and in that department Google just jumped even further ahead of its main competitor, Yahoo.

The number of clicks on Mountain View, Calif.-based Google's Web site increased nearly 20 percent in April compared with a year ago, according to several analysts who yesterday cited data from the research firm comScore.

That was Google's biggest such increase since November, when comScore said its ad-click count rose 27 percent, according to a report by UBS Investment Research.

Clicks on Sunnyvale, Calif.-based Yahoo, which already is far behind Google in ad clicks, fell 4 percent in April.

Google shares rose $14.76, or 2.6 percent, to $583 at the close of trading. Yahoo's stock price fell 9 cents, or 0.3 percent, to close at $27.07.

A Google spokesman said the company doesn't comment on comScore figures, and Yahoo executives did not immediately respond to a request for comment.

Analysts tend to be cautious about comScore data, which they say doesn't track all Internet searches and sometimes can be misleading. Last month, for example, Google reported ad revenue to the federal government that turned out to be much higher than what analysts relying on comScore data had predicted.

Still, comScore generally remains highly regarded. Just two weeks ago, it drew great attention when it found Google had become the nation's most popular Web site by surpassing Yahoo in the number of unique monthly visitors. Some analysts were impressed yesterday by its latest ad-click data.