Yet average FiCO [consumer credit] scores for the pool, percent of no-doc["Liar"] loan to value measures and other indicators were pretty static.... The point is that these measures could stay roughly static, but the overall pool of mortgages being issued, packaged and sold off was worsening in quality, because for the same average FICO scores or the same average loan to value, you were getting a higher percentage of interest only mortgages.-The Big Short by Michael Lewis
I don't know what "value measures" part exactly means.