Effectiveness of prayers of intercession

A randomized controlled experiment by Leibovici (2001) shows not only that remote intercessory prayer yields statistically significant results, but that it does so retroactively.

The experiment studied the effects of prayer on 3393 people that had been in years before the experiment.

As we cannot assume a priori that time is linear, as we perceive it, or that God is limited by a linear time, as we are, the intervention was carried out 4-10 years after the patients' infection and hospitalisation. The hypothesis was that remote, retroactive intercessory prayer reduces mortality and shortens the length of stay in hospital and duration of fever.

Of the three measures (mortality, length of stay in hospital and duration of fever), two were significantly enhanced by prayer (and one not significantly):

Mortality was 28.1% (475/1691) in the intervention group and 30.2% (514/1702) in the control group (P for difference=0.4). Length of stay in hospital and duration of fever were significantly shorter in the intervention group than in the control group (P=0.01 and P=0.04, respectively).

_{Leibovici L (2001). "Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial". BMJ 323 (7327): 1450–1. doi:10.1136/bmj.323.7327.1450}

The letters to the publisher about the article are an interesting read (and not very long, either). Probably the most important point is to have caution with conclusions. Some points to consider about the experiment are

• It's not specified who prayed and to whom. If Baal was prayed to, the results don't say anything about the Judeo-Christian God. (But Leibovici is a Jewish name and the experiment was conducted in Israel, so it's possible it wasn't Baal.)
• The result might be a type I statistical error (rejecting a true null hypothesis). Given the large sample size, it's improbable, but by definition possible.

• The author states the purpose of the article was not to study religion, but to show that empirical methods shouldn't be used for testing questions "completely outside the scientific model of the physical world."

  The purpose of the article was to ask the following question: Would you believe in a study that looks methodologically correct but tests something that is completely out of people's frame (or model) of the physical world—for example, retroactive intervention or badly distilled water for asthma?

  [...]

  The article has nothing to do with religion. I believe that prayer is a real comfort and help to a believer. I do not believe it should be tested in controlled trials.

There is, fundamentally, a problem in attempting to analyse results as evidence of intercession: correlation is not the same as causality; stating that "we prayed for him, and he recovered" is not the same as demonstrating "we prayed for him and this is what caused him to recover". He could have recovered through any number of routes:

• natural body recovery
• medical help (I've heard that can help)

Ultimately, there is no "control group" in an individual scenario such as this to provide any meaningful way of interpreting the result. Additionally, a single event has absolutely no statistical relevance; at the individual level, all bets are off. As Rex Kerr has already noted, attempts to scientifically study this (with proper control groups, etc) have not gone so well.

Another issue here is the human mind's ability to celebrate success and forget failure (similar to the way in which a gambler forgets all the many times he has lost, and uses the fewer number of wins to justify their habit):

• when the desire of the prayer works, it is often shouted from the rooftops, used in headlines as evidential proof, etc
• when it doesn't, people are reasonably sad (quite often it means somebody has died), but it is not given the same announcement; I really can't envisage a headline "Alleluia! Our prayers for Tony's illness have been answered! God has spoken! He died." (please forgive the morbid tone)

My point in the above is not to say "prayer is useless", but rather: the anecdotal evidence is itself naturally biased towards to positive; since the negative is dismissed.

In my view; if you feel that prayer helps, pray. A good friend of mine had these sage words to say on the effectiveness of prayer:

In my view, God's already with this newly growing family, and is looking after them and loving them. That's what God does. I waver greatly in terms of what prayer does, what it can accomplish etc, but I think I'm generally of the opinion that it's more to influence our actions than God's. If praying makes me more aware of their needs, even just by giving me space to consciously think of what they might be going through and how I could help, how is that a bad thing?

These are not my words, so please don't interpret "more ... than God's" as me saying prayer doesn't work - but if prayer causes the praying person (the pray-er?) to act more towards the goal, then in that sense it might demonstratively work (to the non-theist: reflection may achieve a similar aim).

The best analysis/meta-analysis I know of regarding intercessory prayer has been conducted by the Templeton Institute, with a negative result. Thus, there is presently no statistical support for the belief that prayer will be answered in an obvious or measurable way.

However, praying for intercession need not necessarily be done because you think God will listen to your individual plea and change outcomes accordingly. It could also be done because you have hopes for how things will turn out and want to express those hopes in a meaningful way.