When asked about incomes in surveys, both women and men tend to report that the woman earns slightly less than the man. In many cases, however, a glance at administrative data on actual incomes does not substantiate these reports. In cases where the woman earns more than her partner, many respondents adjust the woman’s income share in order to comply with the “male breadwinner norm”. Couples are more likely to misreport if the woman is just as or less educated or if she works less hours than the man, but still earns more. These are the findings of a study conducted by ZEW Mannheim together with the University of Basel.

A man and a woman sit in front of a laptop and compare documents.
Some couples understate the woman’s contribution to the couple’s income.

The researchers compared income information from a survey conducted in Switzerland with the respondents’ income data from administrative data sources. In the survey, many participants report that the woman earns slightly less than or just as much as her partner. Administrative data for the same persons, however, show a discrepancy between reported and actual incomes for many couples where women actually earn more.

Gender norms influence reported incomes

Income misreporting occurs especially if the woman’s income share accounts for more than 50 per cent of the couple’s income. Both men and women misreport incomes of both themselves and their partners, with the tendency going toward overstating men’s incomes. According to the authors of the study, the fact that women’s income contributions are systematically underreported to account for just less than 50 per cent of the overall income provides evidence of couples adjusting to comply with the male breadwinner norm, according to which the man should earn more.

“Our data show that misrepresentations of income are particularly prevalent among couples in which the woman is just as or less educated than the man but earns more,” says Dr. Michaela Slotwinski, a researcher in the ZEW Research Department “Social Policy and Redistribution” and co-author of the study. “This could be due to the fact that admitting that the woman earns more, despite having the same or even a lower level of education, could pose a particular threat to male identity. The same is true for cases where women work less or the same number of hours and still have a higher income. These couples are also more likely to misrepresent their income situation.”

The study further shows that both men and women already tend to underreport the woman’s income share when it accounts for between 48 and 50 per cent. This could be interpreted as “precautionary misreporting” so as to prevent the case, where the woman’s reported wage accidentally exceeds her husband’s earnings.

Survey data could overstate the gender wage gap

So while it could be concluded, based on survey data, that women adapt their labour market decisions so as not to earn more than their partner, it has been found that this is not the case. Instead, the study suggests that couples merely adapt their reported incomes to comply with the norm as soon as the woman’s share of total income reaches about 48 per cent. As a consequence, survey data might be less informative about individuals’ behaviour than previously expected.

“Income misreporting leads to women’s earnings being systematically underestimated and men’s earnings being overestimated in survey data. Such potential survey biases can, for instance, make the gender wage gap seem larger than it actually is,” explains Michaela Slotwinski. “This could in turn have consequences for how political measures for overcoming the gender wage gap are designed, if these are based on surveys.” The study documents that the gender wage gap is overstated by nine to thirteen per cent if its calculation is based on survey data. If, for instance, the actual gender wage gap amounts to approximately ten per cent, the gender gap based on survey data would be estimated to range between 10.9 and 11.3 per cent.




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