It is not so much the absolute figure, the change is far more important. The survey released this morning (The Univ. of Michigan Consumer Sentiment Index (MCSI) was down 10% over prior month. Anything greater than a 5% move is considered significant, with a 2% sampling error. This particular index randomly calls and gets just 500 responders to 50 questions.
The more accepted and generally used consumer confidence index (CCI) is from The Conference Board, an indy research group. They contact 5,000 each month, and seek the same type of data.
Both are started and pegged to a certain year, which started the reading at 100. So there is an actual score, but it is the trend in either direction month to month that is most important.
Manufacturers and retailers actually take these trends into consideration for production and inventory planning, perhaps even hiring and layoffs. Although, there is much much more involved, as I am sure you are aware that supply chain logistics have become very complex and advanced.