A randomized doubleblind experience studied whether magnetic

A randomized, double-blind experience studied whether magnetic fields applied over a painful area can reduce pain intensity. The subjects were 50 volunteers with postpolio syndrome who reported muscular or arthritic pain. The pain level when pressing a painful area was graded subjectively on a scale from 0 to 10 (0 is no pain, 10 is maximum pain). Patients were randomly assigned to wear either a magnetic device or a placebo device over the painful area for 45 minutes. Here is a summery of the pain scores for this experiment, expressed as means ± standard deviations. Pretreatment: Magnetic Device (n=29): 9.6 ± 0.7 Placebo Device (n=21): 9.5 ± 0.8 Posttreatment: Magnetic Device (n=29): 4.4 ± 3.1 Placebo Device (n=21): 8.4 ± 1.8 Change: Magnetic Device (n=29): 5.2 ± 3.2 Placebo Device (n=21): 1.1 ± 1.6 Is there good evidence that the magnetic device is better than a placebo equivalent at reducing pain? How much reduction in pain is achieved with the magnetic device? Give a 95% confidence interval for the mean difference in pain scores pre- and post-treatment among patients given the magnetic device. What procedure did you use and why?

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