by Rocio Sanchez-Moyano Research Assistant |
With the continued growth of house prices across the
country, talk of a housing bubble is beginning to reappear in the
headlines. House price-to-income ratios
are often used to indicate a bubble, as prices have historically had a
relatively stable relationship with incomes (both mean and median). In the US, nationally, the price-to-income
ratio remained relatively stable throughout the 1990s. It began to increase around 2000 and
surpassed its long-run average of 3.65 by 2002 (Figure 1). The national price-to-income ratio continued
to increase in the mid-2000s, reaching a high of 4.63 in 2006 before rapidly
declining in 2007 and 2008 and eventually hitting a low of 3.26 in 2011. The classic bubble shape is clearly visible
in this trend. Recent price gains,
viewed in this context, do not seem to indicate the return of a bubble;
price-to-income ratios today match their early 1990s rates and still have some
room for growth before reaching their long-run average. (Click chart to enlarge.)
Notes:
Prices
are 1991 National Association of Realtors® Median Existing Single-Family Home
Prices, indexed by the FHFA Expanded-Data House
Price Index. Incomes are median household
incomes.
Sources: JCHS tabulations of FHFA
Expanded-Data House Price Index; US
Census Bureau, Moody’s Analytics Estimates.
However, despite the seemingly straightforward relationship
between house prices and incomes in Figure 1, this indicator can be difficult
to interpret. To start, many data
sources are available for measuring prices.
One used frequently is the National Association of Realtors ® (NAR) Single-Family
Median Home Price as it is widely available for many metros and provides an
actual house price (rather than an index showing change in values) that can be
compared to income levels. The
disadvantage to this measure is that NAR house prices also capture changes in
the types of units that are being sold over time and so does not reflect how
the value of the same home changes. Repeat sales indices, like the Federal
Housing Finance Authority’s (FHFA) Expanded-Data House Price Index, which was
used to produce the figures in this post, are designed to take into account
changes in the values of homes themselves by tracking sales of the same homes
over time. However, the FHFA index can
be more difficult to interpret since, as an index, it does not provide
information about current prices. Price-to-income ratios using this data must
peg the index to a starting or ending house price.
Furthermore, identifying bubbles or other price anomalies
from price-to-income ratios can be difficult because it is not clear what is an
appropriate baseline value of the measure for comparison. Even in the aggregate US case, where the
ratio did not fluctuate more than one percent in either direction for much of
the 1990s, the linear trend is not flat and the long run average is above the
1990s levels. This becomes even murkier
when observing trends at the metro level.
Some metros, like Dallas, had stable price-to-income ratios over the
last two decades (Figure 2). Dallas did
not experience a significant bubble in the mid-2000s and its long-run average
mirrors the linear trend. In other
metros, like Phoenix, the boom-bust period led to significant fluctuations in
the price-to-income ratio after having been relatively stable in the 1990s. If the 1990s levels are to be considered
normal for Phoenix, then current price-to-income ratios remain below average
and recent growth in prices can be considered a return to normal after an
overcorrection.
For other metros, the price-to-income trend is more
difficult to interpret. Ratios in
Cleveland are well below their long-run average, but the historical trend has
been drifting downwards, so ratios in recent years could be indicating a reset
of the ratio in Cleveland to lower levels.
At another end, San Francisco has experienced a wide range of
price-to-income ratios in recent history.
Price-to-income ratios boomed in the late 1980s, decreased throughout
much of the 1990s, and then surged through the mid-2000s. Compared to its long-run average, ratios in
San Francisco are above historical norms, but, when the historical trend is
considered, prices can continue to increase before they appear “too high.” Finally, if a fundamental relationship exists
between prices and incomes, it is unclear why the ratio can vary significantly
from metro to metro. The national
average is around 3.6. In the metros
observed here, Cleveland and Dallas both have historic averages below 3.0 while
San Francisco’s is double the national average. (Click chart to enlarge.)
Notes: Prices are
1991 National Association of Realtors® Median Existing Single-Family Home
Prices, indexed by the FHFA Expanded-Data
House
Price Index. Incomes are median household incomes.
Sources:
JCHS tabulations of FHFA Expanded-Data House Price Index; US Census Bureau, Moody’s Analytics Estimates
Given this variation, what can we make of the
price-to-income ratio? On a national
level, this ratio does a relatively good job of identifying substantive shifts
in the market. In the aggregate, there
appears to be a “normal” price-to-income ratio and prolonged deviation from
this trend can signal an underlying shift.
However, on a metro-by-metro level, where it can be difficult to
identify an appropriate baseline value, long-run historical context is
necessary to interpret point-in-time estimates.
In markets like Dallas and Phoenix, historical trends are consistent
enough that it can be useful to compare the current ratio to past ones. In others, like Cleveland and San Francisco, the
price-to-income ratio on its own is not especially helpful since there is no
clear way to identify a “normal” price-to-income ratio.