A number of years ago, an experiment was performed by a church in Phoenix, Arizona.
They randomly selected 160 names from the local phone book and divided them into two, 80 in each group.
The first group was prayed for daily by their team of intercessors. The second group was not prayed for.
After 90 days, all 160 homes were called by members of the intercessory team. They identified themselves and asked for permission to stop by and pray for the family and any needs they might have. Of the 80 homes that were not prayed for, one person invited them to come in. Of the 80 homes that had been prayed for, 69 invited someone to come over, and of the 69, 45 invited them to come in.
Prayer makes a difference!
(Story comes from Alvin Vander Griend in The Praying Church Idea Book by Douglas A. Kamstra)