Questions 11-21 are based on the following
passage.
This passage is adapted from Jeffrey Mervis, “Why Null Results Rarely See the Light of Day.” ©2014 by American Association for the Advancement of Science.
The question of what to do with null
results—when researchers fail to see an effect that
should be detectable—has long been hotly debated
among those conducting medical trials, where the
5 results can have a big impact on lives and corporate
bottom lines. More recently, the debate has spread to
the social and behavioral sciences, which also have
the potential to sway public and social policy.
There were little hard data, however, on how often or
10 why null results were squelched. “Yes, it’s true that
null results are not as exciting,” political scientist
Gary King of Harvard University says. “But I suspect
another reason they are rarely published is that there
are many, many ways to produce null results by
15 messing up. So they are much harder to interpret.”
In a recent study, Stanford political economist
Neil Malhotra and two of his graduate students
examined every study since 2002 that was funded by
a competitive grants program called TESS
20 (Time-sharing Experiments for the Social Sciences).
TESS _allows_ scientists to order up Internet-based
surveys of a representative sample of US adults to test
a particular hypothesis (for example, whether voters
tend to favor legislators who boast of bringing federal
25 dollars to their districts over those who tout a focus
on policy matters).
Malhotra’s team tracked down working papers
from most of the experiments that weren’t published,
and for the rest asked grantees what had happened to
30 their results. _In their e-mailed responses, some
scientists cited deeper problems with a study or more
pressing matters—but many also believed the
journals just wouldn’t be interested. “The
unfortunate reality of the publishing world [is] that
35 null effects do not tell a clear story,” said one
scientist._ _Said another, “Never published, definitely
disappointed to not see any major effects.”
Their answers suggest to Malhotra that rescuing
findings from the file drawer will require a shift in
40 expectations._ “What needs to change is the
culture—the author’s belief about what will happen if
the research is written up,” he says.
Not unexpectedly, the statistical strength of the
findings made a huge difference in whether they
45 were ever published._ _Overall, 42% of the experiments
produced statistically significant results. Of those,
62% were ultimately published, compared with 21%
of the null results._ _However, the Stanford team was
surprised that researchers didn’t even write up
50 65% of the experiments that yielded a null finding.
Scientists not involved in the study praise its
“clever” design. _“It’s a very important paper” that
“starts to put numbers on things we want to
understand,” says economist Edward Miguel of the
55 University of California, Berkeley.
He and others note that the bias against null
studies can waste time and money when researchers
devise new studies replicating strategies already
found to be ineffective._ _Worse, if researchers publish
60 significant results from similar experiments in the
future, they could look stronger than they should
because the earlier null studies are ignored.Even
more troubling to Malhotra was the fact that two
scientists whose initial studies “didn’t work out”
65 went on to publish results based on a smaller sample.
“The non-TESS version of the same study, in which
we used a student sample, did yield fruit,” noted one
investigator.
A registry for data generated by all experiments
70 would address these problems, the authors argue.
They say it should also include a “preanalysis” plan,
that is, a detailed description of what the scientist
hopes to achieve and how the data will be analyzed.
Such plans would help deter researchers from
75 tweaking their analyses after the data are collected in
search of more publishable results.