The Center on Philanthropy at Indiana University faces criticism of its top research program, which is to compile data for the annual “Giving USA” report.

Many not-for-profits benchmark their fundraising results against the “Giving USA” study, which is due out in June.

“Giving USA” has greatly underestimated the drop in charitable giving during the recession, the Chronicle of Philanthropy reported last month. A recent IRS estimate shows that itemized charitable contributions in 2009 may have declined as much as 14 percent.

In contrast, “Giving USA” reported last year that Americans’ charitable contributions didn’t decline at all in 2009, and that they fell just 2.4 percent in 2008.

IRS data shows that Americans actually wrote off $172.9 billion in charitable contributions in 2008, a 10.6-percent drop from 2007.

“Giving USA” is published six months after the close of the year, while the IRS takes two to three years to release its numbers, the Chronicle noted. Another difference in “Giving USA” is that it tries to account for poor and middle-class Americans who don’t itemize their taxes and wealthy people who give more than the IRS limit on deductions.

Nevertheless, the Center on Philanthropy has tweaked its methodology. Executive Director Patrick Rooney told the Chronicle that the revision will account for changes in consumer confidence and patterns in consumption. The next “Giving USA” will contain revised figures for 2008 and 2009.