The substantial drop in credit card debt in the United States since early 2009 has been widely attributed to newly frugal consumers. But analysts say that a significant portion of the decline is actually the result of financial institutions writing off billions of dollars in credit card debt as losses.

While consumers have done their part by shying away from exceeding new credit limits and turning increasingly to debit cards, the question is to what extent are consumers voluntarily reducing their balances, and to what extent are banks making the decision for them.

The answer has wide implications for the broader economy as banks try to determine whom to extend credit to - and how much - and as businesses try to adapt to the changes in consumers’ spending patterns.

‘There is a lot of debate going on right now among economists,