

Effects of retroactive prayer on outcomes in patients with infection (2001) - gwern
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC61047/

======
jnevill
This article was submitted to BMJ as part of their ironic Christmas edition.
However the gullible still routinely cite it. You can see a response here
([http://www.bmj.com/content/324/7344/1037](http://www.bmj.com/content/324/7344/1037))
from the Papers author as well as others. And a piece from RetractionWatch.com
about the article [http://retractionwatch.com/2014/12/23/irony-place-
science/](http://retractionwatch.com/2014/12/23/irony-place-science/)

------
rwolf
Note the timestamp on the article and compare to:
[http://www.theatlantic.com/technology/archive/2014/12/the-
et...](http://www.theatlantic.com/technology/archive/2014/12/the-ethics-of-
sarcastic-science/383988/)

------
jbellis
To a non-expert, it looks like studies on prayer are a mixed bag. This meta-
analysis found no effect:
[http://link.springer.com/article/10.1207/s15324796abm3201_3#...](http://link.springer.com/article/10.1207/s15324796abm3201_3#page-1)

But this one did:
[http://rsw.sagepub.com/content/17/2/174.short](http://rsw.sagepub.com/content/17/2/174.short)

Another interesting study:
[http://online.liebertpub.com/doi/abs/10.1089/107555304132380...](http://online.liebertpub.com/doi/abs/10.1089/1075553041323803)

("No direct intervention effect on the primary outcomes was found. A
marginally significant reduction in the amount of pain was observed in the
intervention group compared to controls. The amount of concern for baseline
problems at follow-up was significantly lower in the intervention group when
stratified by subject's baseline degree of belief that their problem could be
resolved. Prayer intervention appeared to effectively reduce the subject's
level of concern only if the subject initially believed that the problem could
be resolved. Those in the intervention group who did not believe in a possible
resolution to their problem did not differ from controls. Better physical
functioning was observed in the intervention group among those with a higher
belief in prayer and surprisingly, better mental health scores were observed
in the control group with lower belief in prayer scores.")

~~~
diminoten
The linked study is a gag study, and didn't actually take place.

Think about it -- _retroactive_ prayer? As in, the people got sick, either
died or got better, and were _then_ prayed for?

I mean, being an omnipotent deity is one thing, but effective _retroactive_
prayer? Now that's a neat trick.

~~~
steverb
It fits with the logic though. If your god is omnipotent, then whether you
pray before or after death shouldn't make any difference.

I suppose, given the existence of a deity that is able to heal people, then
this would be a decent way to determine whether or not said deity was truly
omnipotent.

~~~
JadeNB
> It fits with the logic though. If your god is omnipotent, then whether you
> pray before or after death shouldn't make any difference.

Perhaps also 'omniscient': if your god is all-knowing, then it need not wait
until you pray to act on your prayer.

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harshreality
How do they know members of the control group weren't being prayed for?

Even assuming the study were perfect, the conclusion is not that retroactive
prayer works, but that retroactive prayer in the context of conducting a
scientific study works, since if you believe the deity being prayed to exists,
you also have to believe that the deity knows it's part of a scientific study
and not genuine spontaneous prayer.

~~~
gwern
> How do they know members of the control group weren't being prayed for?

Randomization should balance confounders like that: there should be on average
an equal number of pre-prayed-for people in both the experimental and control
groups.

(And even if all subjects had been prayed for, it seems reasonable that prayer
would be additive and one would still expect to detect an average treatment
effect.)

------
tjradcliffe
[Edit: yeah, I know it's a gag study, but this analysis still stands. Even if
the study had been performed it would have issues, and it is worth pointing
those issues out.]

I wonder if their p-values are Bonferroni corrected?

That is, they ran three different experiments (that they reported on) and so
the significance of their results should be concomitantly reduced.

Consider: if you examined a hundred different outcome measures between control
and treatment groups in any given study you would be almost certain to find at
least one that by chance alone was different at a p=0.05 level. The Bonferroni
correction (or some variant of it--there are numerous similar approaches that
go by different names) adjusts for this.

Failure to correct p-values for multiple experiments is one of the most common
causes of spurious results in otherwise apparently well-designed studies.

Furthermore, they don't actually include the raw data, don't give a detailed
description of their method of analysis ("The χ2 test was used to test for the
significance of the results shown in the tables. As most of the continuous
variables did not have a normal distribution, the Wilcoxon rank sum test was
used for comparisons" is no-where near sufficient for me to reproduce their
results) and base their "fever" indicator on multiple measures of which they
take one.

Also, their control group has a maximum hospital stay of over twice that of
their treatment group. How do the p-values vary if you look at large sub-sets
of the data? That is, re-run the analysis with 10% of the data left out. Do
the effects persist? This is a pretty routine test for robustness, and a claim
with a prior as low as "Retroactive intersessory prayer is effective in
reducing fever and hospital stay duration but not mortality" requires
extremely compelling evidence to increase its plausibility to the point of
being worth bothering with.

Not only is the conclusion questionable on statistical grounds, but also on
theological ones: why would one expect a loving god to intervene to shorten
trivialities on hospital stays and fever duration, but not morality?

The answer cannot be "God works in mysterious ways" because that completely
obliterates any reason for believing that intersessory prayer will ever have
any effect of any kind. It is equivalent to the claim that god is a black box
that has a completely random and unpredictable response to stimuli (prayer) so
we should study which stimuli have predictable outcomes.

~~~
gwern
> Even if the study had been performed it would have issues, and it is worth
> pointing those issues out.

What amuses me is that a lot of real research papers would flunk your
criteria. To pick just one:

> Furthermore, they don't actually include the raw data,

So, do you see papers providing the raw data _often_? I don't.

