There have been plenty of scientific studies showing
associations between Television and academic mediocrity,
depression, aggression, poor concentration, obesity,
consumerism, civic disengagement, etc.
You would almost think that TV might be bad for you!
For lovers and defenders of TV, how to fight back? Luckily
for them, two economists have come to the rescue, providing
a statistical study showing that TV really is good for kids.
According to “The Benefits of Bozo“, the Slate article
describing their study:
http://www.slate.com/id/2136372/
…“In a recent study, two economists at the University of Chicago,
Matthew Gentzkow and Jesse Shapiro, came up with a different
way to test the long-run impact of television on kids—by reaching
back to the distant past of the information age. When Americans
first started getting television in the 1940s, the availability
of the medium spread across the country unevenly. Some cities,
like New York, had television by 1940. Others, like Denver and
Honolulu, didn’t get their first broadcasts until the early 1950s.
Whenever television appeared, kids became immediate junkies:
Children in households with televisions watched their boob tubes
for close to four hours a day by 1950.”
…“The key point for Gentzkow and Shapiro’s study is that depending
on where you lived and when you were born, the total amount of TV
you watched in your childhood could differ vastly. A kid born in
1947 who grew up in Denver, where the first TV station didn’t get
under way until 1952, would probably not have watched much TV at
all until the age of 5. But a kid born the same year in Seattle,
where TV began broadcasting in 1948, could watch from the age
of 1. If TV-watching during the early years damages kids’ brains,
then the test scores of Denver high-school seniors in 1965
(the kids born in 1947) should be better than those of 1965
high-school seniors in Seattle.”
“From the 1966 Coleman Report, the landmark study of educational
opportunity commissioned by the Civil Rights Act of 1964, Gentzkow
and Shapiro got 1965 test-score data for almost 300,000 kids.
They looked for evidence that greater exposure to television
lowered test scores. They found none. After controlling for
socioeconomic status, there were no significant test-score
differences between kids who lived in cities that got TV earlier
as opposed to later, or between kids of pre- and post-TV-age
cohorts. Nor did the kids differ significantly in the amount
of homework they did, dropout rates, or the wages they eventually
made. If anything, the data revealed a small positive uptick in
test scores for kids who got to watch more television when they
were young. For kids living in households in which English was
a second language, or with a mother who had less than a high-school
education, the study found that TV had a more sizable positive
impact on test scores in reading and general knowledge. Evidently,
Bozo the Clown was better than we remember.”
The conclusion above gives the impression that this study is actually
looking at the test results of kids who grew up watching a lot of
TV compared to kids who grew up watching substantially less.
That is actually not the case, instead this study is comparing the
test results of whole cities. That is, the authors assume that in a
city where a TV station started broadcasting a few year earlier,
that children living there watched substantially more TV growing
up than children who grew up in a city where a TV station came later.
This is a huge assumption to make. For example, the study is comparing
cohorts where a TV station arrived in their city in 1948 with cohorts
where a TV station arrived in 1954. As their own graph shows in 1948
only about 20% of households even had TVs, and by 1954 that percentage
had only increased to about 30%. (Remember, back in the 1940s and 1950s,
a TV was an expensive luxury item.) So basically the test results are
diluted (unevenly) by a large percentage of kids who lived in homes
without a TV (despite living in a city with a TV station).
Also, there is no real evidence that children, in the 1950’s, living
in households with a TV instantly started watching over 4 hours of TV
per day (as the Slate article argues). There is some evidence that
in homes with a TV, that by 1950, the TV was on for 4:35 per day.
Just as by 2008, the average American home has their TV on for 8:18
hours per day. I don’t think that anyone is arguing that today, kids
watch over 8 hours of TV per day.
Never mind the economic, cultural, and demographic differences among
the compared cities. Never mind the fact that it took years from the
time a TV station first arrived for most households to even get a TV.
And never mind, that most new TV stations had few channels making it
hard for even the most dedicated TV fan to actually watch large amounts
of TV right away. These are huge confounding factors.
The authors acknowledge some of these factors, and do attempt to take
them into consideration when doing their statistical calculations.
Nevertheless, there are a large number of known and unknown confounding
historical factors making it impossible to come to any kind of accurate
conclusion. This explains why this “working paper” was never published
in a peer-reviewed journal (note it was released in January 2006, so
there has been plenty of time for peer-review). This lack of peer-view
did not stop Slate from publishing an enthusiastic and uncritical
article describing this non-peer-reviewed study, as “Proof that TV
doesn’t harm kids”.
This non-peer-reviewed study is called Does Television Rot Your Brain?
and was written by Matthew Gentzhow and Jesse Shapiro. If you go to
Jesse Shapiro’s website he does not list “Does Television Rot Your Brain?”.
http://www.nber.org/papers/w12021.pdf
(it can be downloaded by registering at SSRN.com)
Instead of using a large number of assumptions and estimates to try to
compare a large group of kids (some of who grew up watching various amounts
of TV) with another group of kids (some of who watched slightly less),
why not just do a longitudinal study?
http://en.wikipedia.org/wiki/Longitudinal_study
Actually, researchers at Otago University in New Zealand did exactly that.
What they found was this:
http://archpedi.ama-assn.org/cgi/content/full/159/7/614
Note: a Slate commenter makes the following excellent point:“These findings indicate that excessive television viewing is likely
to have a negative impact on educational achievement. This is likely
to have far-reaching consequences for an individual’s socioeconomic
status and well-being in adult life.23 Although we cannot prove that
watching television is causally related to poor educational achievement,
the associations between viewing time and educational outcomes were
strong and independent of the known confounding influences of intelligence,
socioeconomic status, and childhood behavioral problems. Furthermore,
this study fulfills many of the other criteria often used to infer
causality in an observational study, including temporal sequence,
dose-response relationship, and biological plausibility. However, we
cannot rule out the possibility of reverse causation. This is likely
to be at least part of the explanation for the strong association
between television viewing during adolescence and leaving school
without any qualifications. By adolescence, some individuals will
be poorly motivated toward schoolwork and may, for example, fill
their time by watching television instead of doing homework. This
is less likely to be the explanation for the strong inverse association
between television viewing in childhood and attainment of a university
degree. The finding that childhood viewing was a better predictor than
adolescent viewing of not obtaining a university degree makes reverse
causation unlikely and indicates that excessive childhood television
viewing has a long-lasting association with poor educational outcomes.”
Archives of Pediatrics & Adolescent Medicine (July 2005)
http://fray.slate.com/discuss/forums/th ... ID=2136372“Thinking back to the 1940’s and 50’s it seems to me highly unlikely
that – even in America – TV programmes would have been available
throughout the day(when children were around) and even more unlikely
that the stay-at-home mothers back then would have parked their
children in front of it for long periods. I feel this is reading
back the behavior of today’s families into the past.“
See also a number of studies looking at the effects of TV on school results:
http://www.tvsmarter.com/documents/school.html
As for the issue of Correlation versus Causation see:
http://www.tvsmarter.com/documents/causation.html
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