The first and most commonly studied problem is the rise in unit nonresponse, meaning fewer people are willing to take a survey when asked. Two other growing problems are item nonresponse-- when someone agrees to take the survey but refuses to answer particular questions-- and inaccurate responses. Of course, the three problems can be related. For example, attempts to reduce unit nonresponse by persuading reluctant households to take a survey could raise item nonresponse and inaccurate responses if these reluctant participants rush through a survey they didn't really want to take in the first place.
Unit nonresponse, item nonresponse, and inaccurate responses would not be too troublesome if they were random enough that survey statistics were unbiased, but that is unlikely to be the case. Nonresponse and misreporting may be systematically correlated with relevant characteristics such as income or receipt of government funds. Meyer, Mok, and Sullivan look at survey data about government transfer programs for which corresponding administrative data is also available, so they can compare survey results to presumably more accurate administrative data. In this case, the survey data understates incomes at the bottom of the distribution, understates the rate of program receipt and the poverty reducing effects of government programs, and overstates measures of poverty and of inequality. For other surveys that cannot be linked to administrative data, it is difficult to say which direction biases will go.
Why has survey quality declined? The authors discuss many of the traditional explanations:
"Among the traditional reasons proposed include increasing urbanization, a decline in public spirit, increasing time pressure, rising crime (this pattern reversed long ago), increasing concerns about privacy and confidentiality, and declining cooperation due to 'over-surveyed' households (Groves and Couper 1998; Presser and McCullogh 2011; Brick and Williams 2013). The continuing increase in survey nonresponse as urbanization has slowed and crime has fallen make these less likely explanations for present trends. Tests of the remaining hypotheses are weak, based largely on national time-series analyses with a handful of observations. Several of the hypotheses require measuring societal conditions that can be difficult to capture: the degree of public spirit, concern about confidentiality, and time pressure...We are unaware of strong evidence to support or refute a steady decline in public spirit or a rise in confidentiality concerns as a cause for declines in survey quality."They find it most likely that the sharp rise in the number of government surveys administered in the US since 1984 has resulted in declining cooperation by "over-surveyed" households. "We suspect that talking with an interviewer, which once was a rare chance to tell someone about your life, now is crowded out by an annoying press of telemarketers and commercial surveyors."
Personally, I have not received any requests to participate in government surveys and rarely receive commercial survey requests. Is this just because I moved around so much as a student? Am I about to be flooded with requests? I think I would actually find it fun to take some surveys after working with the data so much. Please leave a comment about your experience with taking (or declining to take) surveys.
The authors also note that since there is a trend toward greater leisure time, it is unlikely that increased time pressure is resulting in declining survey quality. However, while people have more leisure time, they may also have more things to do with their leisure time (I'm looking at you, Internet) that they prefer to taking surveys. Intuitively I would guess that as people have grown more accustomed to doing everything online, they are less comfortable talking to an interviewer in person or on the phone. Since I almost never have occasion to go to the post office, I can imagine forgetting to mail in a paper survey. Switching surveys to online format could result in a new set of biases, but may eventually be the way to go.
I would also guess that the Internet has changed people's relationship with information, even information about themselves. When you can look up anything easily, that can change what you decide to remember and what facts you feel comfortable reporting off the top of your head to an interviewer.