How can NAR sales data drift away from true measure?
It is not definitive if NAR data has a measurable drift other than normal small statistical noise that may arise from not using all MLSs and from any data entry error or local MLSs sending wrong data to NAR. In statistics, one just assumes the positive and negative noises cancel each other out. It is however possible for this statistical noise to drift mostly in one direction and hence cumulatively add up over many years. In our last benchmark in year 2000, we found the reported home sales had a 13 percent upward drift compared to what Census data implied. NAR then revised the past 1990s data to match up with the Census data.
