For the past several months, the Consumer Metrics Institute’s Daily Growth Index has been one of the most interesting data series I follow, and I recommend bookmarking the Institute’s website. Their page of frequently asked questions is an excellent introduction to the service.
The charts below focus on the ‘Trailing Quarter’ Growth Index, which is computed as a 91-day moving average for the year-over-year growth/contraction of the Weighted Composite Index, an index that tracks near real-time consumer behaviour in a wide range of consumption categories. The Growth Index is a calculated metric that smooths the volatility and gives a better sense of expansions and contractions in consumption.
The 91-day period is useful for comparison with key quarterly metrics such as GDP. Since the consumer accounts for over two-thirds of the US economy, one would expect that a well-crafted index of consumer behaviour would serve as a leading indicator. As the chart suggests, during the five-year history of the index, it has generally lived up to that expectation. Actually, the chart understates the degree to which the Growth Index leads GDP. Why? Because the advance estimates for GDP are released a month after the end of the quarter in question, so the Growth Index lead time has been substantial.
Has the Growth Index also served as a leading indicator of the stock market? The next chart is an overlay of the index and the S&P 500. The Growth Index clearly peaked before the market in 2007 and bottomed in late August of 2008, over six months before the market low in March 2009.
The most recent peak in the Growth Index was around the first of September, 2009, almost eight months before the interim high in the S&P 500 on April 23rd. Since its peak, the Growth Index has declined dramatically and is now deep into contraction territory.
It’s important to remember that the Growth Index is a moving average of year-over-year expansion/contraction whereas the market is a continuous record of value. Even so, the pattern is remarkable. The question is whether the latest dip in the Growth Index is signaling a substantial market decline like in 2008-2009 or a buying opportunity like in June 2006. I’ve also highlighted the recession that officially began in December 2007 and unofficially ended last summer. As a leading indicator for GDP, the Growth Index also offers an early warning for possible recessions.
Perhaps the most astonishing chart is the one below, which compares the contraction that began in 2008 with the one that began in January of this year. I’ve reproduced a chart on the Institute’s website and added annotations for the elapsed time and the relationship of the contractions to major market milestones. This chart also shows most clearly the recent plateau effect in the Growth Index.
Among other things, this chart illustrates the more subtle and pernicious nature of the current decline in consumption. The 2010 decline has exceeded the length of the complete 2008 contraction cycle — the combined contraction and recovery.
Fortunately, the current contraction appears to have entered a bottoming process. The key unknown is the extent to which this contraction will have a delayed impact on the metrics that determine GDP and GDP revisions over the next few quarters.