The bad economy continues to cause problems for charity fund raising, according to a new study of giving in the first half of the year.

The study, based on data from more than 800 groups, found that more than half achieved no increases or saw donations drop. Thirty percent of the groups said they had a decline, while 25 percent said giving was flat.

Big organizations are recovering faster than small ones, the study found. About 57 percent of charities with budgets of $3-million or more said contributions rose; when all groups were counted, just 44 percent managed to raise more.

Fund-raising results showed few differences among charities with different causes. The only big gap was among social-service groups and international organizations. Fifty percent of social-service groups chalked up increases compared with 20 percent of international groups.

Charities that spent more on fund raising were doing better than others, the study found.

For instance, six in 10 groups that spent more on e-mail and other Internet fund-raising tactics saw giving rise. However, the survey said, few groups are spending more on those methods: Just 30 percent of charities expanded spending on online efforts.

The study was conducted by the Nonprofit Research Collaborative, a coalition of seven organizations that focus on philanthropy.