Survey Estimates of Wealth - Mathematica Policy Research

eported in public use files and may remove hundreds of billions of dollars from the estimates of
aggregate wealth.
Attempts to measure wealth can produce high rates of nonresponse, either because
respondents are unwilling to report the details of their financial holdings or cannot recall or look
up their account balances. Surveys differ in their approach to editing or imputing missing data,
and if nonresponse is high, the imputation procedures chosen and the level of attention afforded
their execution can have a very substantial effect on the final estimates. Significant bias may be
unavoidable if nonrandom patterns in the nonresponse cannot be fully reflected in the imputation
models. Our analyses detailed in this report suggest that unspecified changes in the Census
Bureau’s imputation procedures may account for some of the evident lack of growth in SIPP
median wealth during much of the second half of the 1990s.
D. EARLIER EVIDENCE ON THE QUALITY OF SIPP WEALTH DATA
The SIPP’s misrepresentation of the trend in median household wealth after the early 1990s
is a clear departure from its earlier performance—and not just with respect to median wealth but
other measures as well. Wolff (1999) compared the SIPP, the SCF, and the PSID with respect to
a number of measures of the size and distribution of wealth over the mid-1980s through the mid-
1990s. His findings suggest that, for the lowest two incomes quintiles, the SIPP did as well as
the SCF in capturing asset holdings, and this comparative performance did not deteriorate a great
deal through the next two quintiles, or through the lower 80 percent of the income distribution.
The SIPP also did particularly well in capturing the major types of wealth held by the middle
class, such as homes, vehicles, and savings bonds; but it did not do so well in capturing the types
of assets held by the wealthiest families.
Ten years earlier, Curtin et al. (1989) reported that the 1983 SCF found a substantially
greater proportion of all households to be in their top income class ($192,000 or more) than did
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