From Reuven Glick and Kevin Lansing, Consumers and the Economy: Household Credit and Personal Saving:
In the years since the bursting of the housing bubble, the personal saving rate has trended up from around 1% to around 6%, while the ratio of household debt to disposable income has dropped from 130% to 118%. Changes over time in the availability of credit to households can explain 90% of the variance of the saving rate since the mid-1960s, including the recent uptrend, according to a simple empirical model.
Obviously, with consumption accounting for 70% or so of GDP, the trajectory of consumption is key to determining growth (as well as to the US current account balance).  Glick and Lansing observe:
… most empirical studies seek to explain movements in the saving rate using movements in the ratio of household net worth to personal disposable income. However, some studies have shown that the behavior of consumption, and by extension saving, is also strongly associated with changes in credit growth. Bacchetta and Gerlach (1997) and Ludvigson (1999) find that credit growth has a significant positive impact on consumption growth in the United States and other countries. In these studies, changes in credit growth can be interpreted as capturing changes in lending practices or other factors that affect consumer access to borrowed money. …
The authors compare the predictions of their model, incorporating this credit channel, against those of a standard net worth based model (that is, using household net worth to disposable income as a determinant). The credit variable is the change in the “measure of credit availability constructed from the Federal Reserve Board Senior Loan Officer Opinion Survey…”
Figure 4 Actual and fitted household saving rates. Source: FRBSF Economic Letter 2011-01
The adjusted R-squareds are 90% vs. 73% for the more restricted model. Thus the evolution of ease of access to credit is going to be key, going forward, to understanding the path of consumption.
Originally published at Econbrowser and reproduced here with permission.