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Thanks to
visiting US academic Stanton Glantz we at last know why young people smoke. In
Toronto last week to tell the Ontario Film Review Board that movies containing
smoking should receive the 18 A rating (that would prevent anyone under 18 from
seeing them unless accompanied by an adult), Glantz told the Post’s James Cowan
that seeing on screen smoking is the main reason why teens start smoking. No
wonder the Post ran the Glantz story on the front page. Since almost everything
about youth smoking, but especially what initiates it, is an immensely
complicated and controversial issue, it is nice to know that this difficult
issue finally has a neat and straightforward solution: just prevent kids from
seeing films with people smoking and they will not smoke.
Glantz’s
“answer” to what makes young people smoke must come as a surprise to any number
of the dozens of serious researchers around the world who study youth smoking
and who turn out hundreds of academic articles a year seeking to understand why,
despite everything that young people know about smoking, they still start to
smoke. For these researchers, the idea that any single thing, let alone
something like seeing someone smoke in a film, could lead over half of the
children, for instance, who became smokers in one study, to start smoking, is
something of a stretch.
But to be fair
to Glantz, he is not making these claims on his own, he is simply the front man
for a group of US researchers, Dalton et al, whose shocking study about youth
smoking and the movies was published in The Lancet (July 26, 2003). The study
looked at 3547 adolescents aged 10-14 who claimed to be nonsmokers. After making
an estimate of how many instances of film smoking the young people would see,
the researchers contacted 2603 of the participants from 13-26 months latter to
determine whether they had started to smoke. What they found was that
adolescents with the highest exposure to movie smoking were 2.71 times more
likely to start smoking than those with the lowest exposure. As they note, while
10% of the young people started smoking during the follow-up period, “52.2% of
smoking initiation in this cohort can be attributed to exposure to smoking in
movies. If the observed association with smoking initiation is assumed to be
causal, reducing movie smoking exposure in this study to the lowest quartile
would have reduced the proportion who initiated smoking during the follow-up
from 10.0% to 4.8%.”
Now what makes
this study a shocking piece of scientific fluff is not simply its conclusion-
which can’t withstand careful scrutiny, but its junk science- that’s the only
term for it- epidemiology. Let’s begin with the epidemiology. At its very best,
epidemiology provides evidence of a statistical association, not causality. A is
associated with B 19 times out of 20, NOT A causes B. There is a strong
association in some European countries in certain years between high numbers of
storks and increased birth rates but the one is not the cause of the other.
Honest practitioners always acknowledge this, particularly when their work is
likely to be reported to a lay audience who might read too much into their
findings. Notice, however, what these researchers say “If the observed
association with smoking initiation is assumed to be causal”. But wait a moment,
this is patently dishonest since the observed association can never be shown to
be causal and therefore there is no reason to assume it to be causal. Causality
can’t come in through the back door.
The problems,
however, don’t stop there. As virtually every researcher on youth smoking knows,
the risk factors- the things that lead kids to begin smoking- are very numerous,
with one well regarded researcher noting over 200 factors. This means that
unless you take these factors into account (control for is the technical term)
in the design of your research you can never be certain that you have even found
a genuine association. Dalton, however only takes account of 14 of the dozens of
factors that are suspected to lead to youth smoking and not even, according to
many researchers, the 14 most significant. In other words she is saying that of
the possibly hundreds of things that influence kids to being smoking, that for
the young people in her study it was seeing smoking in movies and only seeing
smoking in movies that got them started smoking.
Clearly this
claim is false since she didn’t bother to look at most of the other factors to
see whether they- not the movies- influenced her kids. It’s the equivalent of
saying X might be caused by A, B, C, D, E, F and G and we have only studied A
and B but we nevertheless “know” that they cause X. Ten percent of the kids in
Dalton’s study became smokers over a two year period, a figure slightly less
than average. Of this 10% Dalton claims that over half became smokers only
because they were exposed to movies with smoking, even though she admits that
she did not study even a fraction of the other risk factors that might have lead
them to start smoking. In effect, in the end her study really tells us nothing
except for how headline- grabbing bad research can be.
Then too the Dalton
study is challenged by several other problems. Glantz and Dalton fault the
tobacco industry for promoting smoking in films yet the industry stopped paying
promotional money in 1989 while youth smoking began its increase in the mid
1990’s, hardly a brilliant instance of cause and effect. Again, studies show
that young viewers do not rate smoking characters as particularly attractive, so
just how is seeing unattractive people smoking meant to initiate smoking?
Finally, none of the leading and careful accounts of youth smoking by people
like Jessor, Bandura or Ajzen and Fishbein provide any theoretical justification
for Dalton’s movie hypothesis.
Youth smoking
has suffered from twenty years of bad research and simplistic policy
prescriptions pushed by an anti-smoking movement that often appears not only
uninformed but perversely resistant to anything other than its own tired dogmas.
Part of the way forward to finding an answer to why kids smoke is not to buy
into anything as alluringly simplistic and wrong as the Glantz-Dalton show. |
