April 24, 2013

Age-period-cohort

Stuff has a story using data from the NZ General Social Survey.  The data say that people 15-29 are more likely to feel lonely than older people.  The story says that this is a generational change caused by Facebook (they put it a bit less baldly, but that’s the message).

When you find differences between age groups, there are two broad classes of explanations. Epidemiologists call them “age” and “cohort” effects.  An age effect is actually due to age: teenagers today argue with their parents more than 40 year olds do, because that’s what teenagers are like.  Toddlers read less than adults, because they haven’t learned yet. When today’s teenagers get older they will argue with their parents less than they now do; when today’s toddlers get older they will read more than they now do.

Cohort effects are common to a group of people born at the same time.  For example, older New Zealanders are more likely to regard Anzac Day as very important, but we wouldn’t expect today’s teenagers to develop a greater appreciation for it as they get older.  Older people also, on average, have less formal education than 25-35 year olds, but again, todays young Bachelors and Masters graduates are not going to lose their degrees as they age.

So, is the difference in feelings of loneliness between 15-29 year olds and older people an age effect or a cohort effect?  Stuff seems pretty sure it’s a cohort effect — “Generation Net” — but the data say absolutely nothing one way or the other.  Since the NZ General Social Survey started in 2009, there isn’t enough historical data to answer the question, and the US General Social Survey (which has been going since 1972) doesn’t routinely ask a ‘loneliness’ question. The British Social Attitudes Survey, as is so often the case with UK publically-funded data collection, won’t let you see much without becoming a registered user.

There are good reasons to be skeptical about the cohort interpretation.  In 1995, well before social media, Robert Putnam wrote an essay, Bowling Alone, about a rapid decline in social connectedness in the US.  And in the 1920s, the Middletown studies blamed the same sort of changes on the new technologies of radio, film, and automobiles.

However tempting it is to say that the kids these days are different, you do actually need some evidence. More evidence than their constant facebooking and twittering, and showing no respect, and look at what they wear and their music is just noise and they need to get off your lawn.

 

 

[update: The Herald has a more balanced story]

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    David Welch

    Yes, exactly what I thought when I saw their headline. It’s pretty obvious that young people can be miserable and making friends or getting used to not having them is something learnt with age. This is backed up by studies of loneliness: the quote below is from a literature review.

    “…contrary to popular belief and depictions, loneliness more frequently occurs during earlier developmental periods compared to old age (Peplau et al., 1982 and Perlman and Landolt, 1999). For example, in a large-scale survey, Parlee (1979) found that 79% of participants aged under 18 years reported feeling lonely sometimes or often, as opposed to 71% of 18- to 24-year-olds, 69% of 25- to 34-year-olds, 60% of 35- to 44-year-olds, 53% of 45- to 54-year-olds, and 37% of those aged 55 years and older. Schultz and Moore (1988) have also observed high school students to be lonelier than college students, although loneliness has been reported to be widespread during the initial college transition (Cutrona, 1982 and Shaver et al., 1985). Indeed, Culp, Clyman, and Culp (1995) found that 66% of high school students considered loneliness to be a problem that they had experienced in the past year. In a review of mean loneliness scores, Perlman and Landolt (1999) concluded that the prevalence of loneliness appears to peak during adolescence, drop between young adulthood and middle age, and then perhaps rise slightly in old age. Nonetheless, large scale studies conducted by Ostrov and Offer (1978), and Brennan and Auslander (1979, cited in Brennan, 1982), suggest that while more than 50% of adolescents experience recurrent feelings of loneliness, for 10% to 20% of adolescents loneliness is persistent and painful (Brennan, 1982)”

    11 years ago