First American Core Logic says that "on average" home prices across the nation fell 10.2% from April a year ago through this April.
One Tweet away, there was the Case-Shiller number for the 20 City Composite, showing 18.1% price decline for the same period.
Of course, they are not using the same input data, and you can't just arbitrarily say one is wrong. But, that's a pretty big disparity. I tend to like the OFHEO Index better than Case-Shiller, as it takes in more numbers for more areas, generally resulting in less scary reporting over the last couple of years. For the same 12 month period, the OFHEO is showing only a 6.8% average national drop. There are definite differences in the OFHEO and Case-Shiller methodologies., but now we're looking at three numbers, all using variations of "national average" for price drops, and ranging from 6.8% to 18.1%, a 167% larger price decline.
Maybe we can just average the three, calling it the "Who Knows Index?" That number would be 11.7%. Seriously, the differences in sampling areas and methodologies could make all of these partially correct. But, the general public is presented with the use of the words "national," "average," and the same time frame. Who wouldn't be confused?