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On a cold January evening, Clare walks the streets of north London, armed with a file of addresses and maps. She wants to interview people for Britain's Labour Force Survey (LFS), which is the basis for a host of important economic statistics including the unemployment rate. Her job, like that of many surveyors across the developed world, has been getting harder.
Corralling interviewees has always been tough, particularly in London. Clare sometimes feels like a private detective as she befriends porters to enter gated communities. "It was the rule to be welcomed in, whereas now you can't count on it," she says. Of the five doorbells she rings, the most positive answer is that now is “not a good time.” Clare is hopeful about the phone call arranged for the following day.
Response rates to surveys are plummeting all across the developed world. Last year only around ４３% of households contacted by the British government responded to the LFS, down from ７０% in ２００１. In America the share of households responding to the Current Population Survey (CPS) has fallen from ９４% to ８５% over the same period. The rest of Europe and Canada have seen similar trends.
Poor response rates drain budgets, as it takes surveyors more effort to hunt down interviewees. In addition, a growing reluctance to give interviewers information threatens the quality of the data. Although politicians often complain about inaccurate election polls, when economic surveys are misleading there can be consequences for the public.
Household surveys derive their power from randomness. Since it is impractical to get every citizen to complete a long questionnaire regularly, statisticians interview what they hope is a representative sample instead. But some types of people are less likely to respond than others — people who live in flats rather than houses, for example. A study by Christopher Bollinger et al. matched data from the CPS with social-security records and found that poorer and very rich households were more likely to ignore surveyors than middle-income ones. Survey results will be skewed if the types of people who do not answer are different from those who do, or if certain types of people are more unwilling to answer some questions or are more likely to
fib.
Statisticians try to correct for these problems. They can adjust the weight given to the answers from underrepresented groups, or fill in blanks with
imputed answers based on those from similar people. To check, they can compare results from household surveys with official administrative data, such as tax records.
Worryingly, mounting evidence suggests that some of these corrections are failing. A study by Bruce Meyer et al. found a widening gulf between the income people declare in surveys and what administrative records suggest. Research by Britain's Behavioural Insights Team, a research group, has also found that the gap between the number of calories that Britons consume and what they report in household surveys widened between １９７４ and ２００８. Another study by Garry Barrett et al. compared household data with national-accounts data between １９６９ and ２０１０ in America, Britain, Canada and Australia. It found that for every percentage-point decline in the response rate, the share of spending captured by household surveys fell by ０.８ percentage points.
For decades, governments have relied on household surveys to set policy. Besides using them to gauge economic indicators, many rely on them for census data. In America, the allocation of over ６００ billion dollars of federal spending is based on the Census Bureau's estimates of the population. Undercounting even a single person can cost a government programme thousands of dollars.
Understanding why people shun surveys might help boost response rates. The most common reasons people give for refusing are that they do not care, that they worry about privacy or that they do not have the time (Clare reports that some non respondents spend ２０ minutes explaining how busy they are). Another factor could be a weakening sense of civic duty — voter participation has also been falling. Over-surveying may also be to blame: the share of Americans reporting that they had been surveyed in the past year more than quadrupled between １９７８ and ２００３. Meyer et al. speculate that what once “was a rare chance to tell someone about your life, is now
crowded out by an annoying onslaught of telemarketers and commercial surveyors."
Statisticians have been experimenting with methods of improving response rates: new ways to ask questions, or shorter questionnaires, for example. In addition, some surveys offer monetary incentives to get the most reluctant interviewees to respond, but such persistence can have drawbacks. One study found that frequent attempts to contact interviewees raised the average response rate, but lowered the average quality of answers.
Statisticians have also been exploring supplementary data sources, including administrative data. Such statistics come with two big advantages. One is that administrative data sets can include many more people and observations than is practical in a household survey, giving researchers the statistical power to run more detailed studies. Another advantage is that governments already collect them, so they can offer huge cost savings over household surveys. For instance, Finland's ２０１０ census, based on administrative records rather than surveys, cost its government just ８５０,０００ Euro (１.１ million dollars) to produce. In contrast, America's government spent １２.３ billion dollars on its ２０１０ census, roughly ２００ times as much on a per-person basis.
Recent advances in computing mean that researchers can now process vast data sets. However, in many developed countries (those in Scandinavia are exceptions), socioeconomic statistics are collected by several agencies, meaning that researchers who want to combine, say, health records with tax data, face formidable bureaucratic and legal challenges.
Governments in English-speaking countries are especially keen to experiment. In January HMRC, the British tax authority, started publishing real-time tax data as an "experimental statistic” for comparison with labour-market data from household surveys. Canada's main statistical agency often uses programmes which are based in part on administrative records. Last year, Britain passed the Digital Economy Act, which will give its Office of National Statistics the right to requisition data from other departments and from private sources for statistics-and-research purposes. America is exploring using such data as part of its ２０２０ census.
Administrative data do have certain limitations. They are not designed for use in statistical analyses. A data set on income taxes may be representative of the population receiving benefits or earning wages, but not the population as a whole. Most important, some things cannot be captured in administrative records, such as well-being, informal employment and religious affiliation.
When administrative data offer no alternative, household surveys,
warts and all, will have to suffice. Statisticians can only fix a biased survey based on other data. In some cases, the only other source available is another survey.
The Economist.
Plunging response rates to household surveys worry policymakers.
１. Which one of the following is closest in meaning to the word
fib?
a. not be truthful
b. not be concerned
c. not be revealed
d. not be involved
e. not be contrived
２. Which one of the following is closest in meaning to the word
imputed?
a. randomly chosen
b. fabricated
c. implicated
d. assigned
e. anonymous
３. Which one of the following is closest in meaning to the phrase
crowded out?
a. made more forceful
b. made less spacious
c. made less ugly
d. made very unappealing
e. made very complicated
４. Which one of the following is closest in meaning to the phrase
warts and all?
a. even with their malicious intent
b. even though they cause offense
c. in spite of their shortcomings
d. in spite of their designs
e. even with their generalities
５. According to this article, which THREE of the following are true?
a. People who conduct surveys in industrialized economies need to protect themselves from aggressive attitudes by interviewees.
b. North London is one of the best places in the United Kingdom to conduct surveys.
c. Lower response rates help to reduce the costs associated with gathering information on the labour force.
d. It is hard to get accurate demographic and economic information because many people are reluctant to provide their personal information.
e. One way to compensate for missing data in surveys in developing countries is to make statistical adjustments to survey results.
f. Administrative data can be a useful substitute for household survey data, but in the past researchers have faced organizational difficulties in utilizing these together.
g. Administrative data offers extra sources of information about people and can reduce the cost of household surveys.
h. It is possible to improve average response rates and the average quality of answers in household surveys by offering additional payment to interviewees.
i. Administrative data cannot be a complete substitute for household survey data because the former cannot cover all types of people.
j. The disparity between figures obtained from household surveys and administrative data is shrinking because the response rates of household surveys are declining.
k. Local governments prefer random data in household surveys because the cost of collecting information on local residents is too high.
６. Which one of the following best describes the main point of this article?
a. One way to raise response rates in developed countries is to inform people that participation in surveys is part of their civic duty.
b. Although technology can overcome problems related to analyzing data from multiple sources, human-created problems are posing new challenges for the use of survey data in developed countries.
c. There is no clear solution to fix the problem of low response rates in developed countries and household data is hard to obtain and difficult to supplement with other sources of data.
d. We should introduce successful approaches found in recent academic studies in order to boost response rates for household surveys in developed countries.
e. In order to raise response rates, those conducting household surveys in developed countries need to take into account the results of household surveys in developing countries.
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