Pay-per-click programs are widely used, but not all marketers have the resources available to properly use them, a new study reveals.

Some 44 percent of e-commerce executives surveyed saying they allocate 20 percent of their entire advertising budgets to PPC. Among those who use PPC programs, all reported using Google, 90 percent said they use Yahoo, 76 percent use MSN, and 27 percent use Ask.com, reports eMarketer, citing an e-tailing group study.

Some 40 percent of respondents admit to managing more than 5,000 keywords; 59 percent said they manage their keywords internally, and among them nearly all allocate the task to three or fewer workers; and 27 percent said they did not know what their cost of conversion was in relation to the total dollar value of each sale.