That is an empirical question...

It is not unusual to find groups with a particular ideological agenda, conservative, progressive, liberal, reactionary, or otherwise that make empirical statements without the rigorous data necessary to back it up. I often assume they have no real interest in trying to corroborate or falsify their claims. But if they really are trying then, bless their little hearts, they just don't know what sort of data they need or how to go about collecting it.

For example, according to Jerry Newcombe the group "40 Days of Life" have been using prayer* against abortion providers, with stunning results:

They claim that, so far, at least 4,313 would-be aborted babies (that they know of) have been saved from the procedure. That's 4,313 babies, presumably bringing joy to their mothers right now. They claim that 53 clinic workers have had a change of heart because of the vigils and have left the abortion field as a result ... 40 Days for Life also claims that, thanks to their efforts, 14 abortion clinics have shut down. Again, this is all because of peaceful prayer vigils, around the clock for 40 days in a row in select cities.

All because of prayer! Or maybe not. I haven't been able to find a thorough analysis of their data on their website, and I am a bit incredulous since the scientific evidence for prayer has been rather lackluster. Maybe it was the fasting.

So what sort of data would they need? Well, for starters, I would like to see the baseline data for abortions provided, staff turnover, and center closings for the same period at abortion providers that weren't subject to directed prayer*. Better yet, they should have a list of providers and randomly select half of the sites for prayer vigils, half for no vigils, and keep track of both. Alternatively, they could run an A-B-A design looking at the variables during pre-prayer baseline, prayer*, and post-prayer baseline to see if prayer stopped having an effect once removed.

There is the further problem that even if one did find a change using the above approaches one couldn't assign that effect solely to the power of prayer. It could be that the mere presence of a vigil has such an effect. To test this they would need to hold a vigil during which the participants do not pray. Should we still see a change, then one couldn't say the effect was due to prayer*. The real test though would be to have a prayer vigil that was in close proximity to abortion providers but not visible to anyone on the street or in the clinic, say a next door office building. That would get to the heart of the power of prayer* in this context.

This particular group has set up such a prayer vigil almost literally within a stone's throw of me. Perhaps I should walk over there and offer my services as a scientific consultant.

*And fasting! Don't forget the fasting!