Why Two Major Surveys Disagree on How Many People Are Lonely

Gallup’s 2023 survey of 142 countries found that 24% of people worldwide report feeling very or fairly lonely. The 2023 U.S. Surgeon General’s advisory, published seven months earlier, states that approximately half of American adults experience loneliness. Both figures are widely cited. Both are defensible. They are not measuring the same thing, and the difference is not a rounding error — it is closer to a factor of two.

This is worth working through carefully, because the instinct when two credible sources disagree this much is to assume one of them is wrong. Neither is. They asked different questions, to different populations, using different instruments, and arrived at answers that describe different slices of the same underlying phenomenon.

What each study actually asked

Gallup and Meta’s State of Social Connections survey, fielded between June 2022 and February 2023, asked roughly 1,000 people aged 15 and older in each of 142 countries a single-item question about how lonely they feel, offering response categories from “very lonely” to “not lonely at all.” The 24% figure Gallup later highlighted combines the “very” and “fairly” lonely categories. Notably, the same dataset found 72% of respondents felt very or fairly socially connected — a reminder, as Gallup’s own follow-up analysis observed, that connectedness and loneliness are not simple inverses. A person can score moderately on both.

The Surgeon General’s advisory does not report a single survey Gallup or the office itself ran. It is a synthesis, and “approximately half” is a summary figure drawn from a body of self-report survey work, including sources like the Harvard Making Caring Common study, which found 36% of Americans reporting serious loneliness in early 2021, with the figure far higher among specific groups — 61% of young adults aged 18 to 25 and 51% of mothers with young children. Cigna’s 2020 workplace-focused survey, using its own loneliness index, found 61% of U.S. adults reporting they sometimes or always feel lonely. The AARP Foundation’s 2018 survey of adults 45 and older used the 20-item UCLA Loneliness Scale, an academically validated instrument, and found one in three lonely by that measure.

None of these four figures agree with each other, let alone with Gallup’s global 24%. That is the pattern worth explaining, not the anomaly worth resolving.

Three sources of the gap

Single item versus multi-item scale. Gallup’s question is a single self-rating: how lonely do you feel, on one scale, asked once. The UCLA Loneliness Scale that AARP used asks twenty separate items about different facets of social experience — feeling in tune with others, feeling part of a group, feeling isolated from others — and aggregates them into a score. Single-item measures tend to produce lower prevalence estimates than multi-item scales, partly because people are more willing to affirm a specific, concrete statement about their social experience (“I feel left out”) than to apply a global label like “lonely” to themselves. Loneliness carries some stigma as a self-description; a scale that never uses the word can surface people who would not tick “lonely” on a single-question survey.

Threshold and time frame. “Sometimes or always feeling lonely,” the frame Cigna used, sets a much lower bar than “very or fairly lonely,” which itself differs from “serious loneliness,” the language Harvard’s researchers used to describe their 36% figure. A measure that counts anyone who feels lonely occasionally will always produce a bigger number than one that counts only frequent or intense loneliness. This is not a flaw in any single instrument. It is a difference in what threshold each was built to detect, and it means the resulting percentages are not directly comparable even when the underlying construct — self-reported loneliness — is nominally the same.

Population and timing. Gallup’s 24% is a global figure, weighted across 142 countries, collected in 2022 and 2023 and covering roughly 77% of the world’s adult population (China was excluded from the survey). The Surgeon General’s synthesis is specific to the United States and draws on data collected mostly during and shortly after the acute phase of the pandemic — a period the Harvard researchers and others have documented as a period of unusually elevated loneliness, particularly among young adults. A global average across 142 countries, most of them not experiencing the same pandemic-era disruption to socializing patterns as the U.S. sample, will look different from a U.S.-specific figure drawn substantially from 2020-2021 data, even before accounting for instrument differences.

Gallup’s own regional breakdowns support this: the global figure conceals wide variation, with young adults aged 19-29 worldwide reporting loneliness at 27%, against 17% for adults 65 and older — a finding that runs counter to a common assumption that loneliness is chiefly a problem of old age. The direction of that age gradient shows up across most of the sources reviewed here, even as the absolute numbers differ by instrument.

Why the disagreement matters more than either number

A 2023 methodological review in BMC Public Health identifies inconsistent measurement as one of the central barriers to progress in this research area — not a footnote to it. When headline prevalence figures move by a factor of two depending on instrument, threshold, and population, any single number reported without its instrument attached is close to meaningless for comparison purposes. A newsroom that quotes Gallup’s 24% in one paragraph and the Surgeon General’s “half of Americans” in the next, without noting they come from different questions asked of different people at different times, produces something that looks like a contradiction rather than what it actually is: two correctly reported figures from two different measurement designs.

This matters practically for anyone trying to track whether loneliness is rising or falling over time, or whether one country has more of a problem than another. Trend claims require the same instrument, applied to comparable populations, at multiple time points. A comparison between Gallup’s single-item global measure in 2023 and AARP’s UCLA Scale figure among Americans 45 and older in 2018 cannot support a claim about change over time or a claim about which population is worse off, because the two measures were not built to be compared to each other in the first place.

What would resolve it

Not a bigger survey. A study designed for comparability would field more than one instrument — a single-item self-rating alongside a validated multi-item scale such as the UCLA Loneliness Scale — on the same respondents, at the same time, in the same countries, and report both. That would let researchers estimate the conversion factor between measures directly, rather than leaving readers to guess why a “quarter of the world” and “half of Americans” can both be true. Absent that, the responsible move is not to average the two figures or pick the more dramatic one. It is to report each figure with its instrument named, and to treat cross-study comparison as an open methodological question rather than a settled fact.