Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

تمرين 130

Pain Management: Laser Therapy "Effect of Helium-Noen Laser Auriculotherapy on Experimental Pain Threshold" is the title of an article in the journal Physical Therapy (Vol. 70, No. 1, pp. 24-30). In this article, laser therapy was discussed as a useful alternative to drugs in pain management of chronically ill patients. To measure pain threshold, a machine was used that delivered low-voltage direct current to different parts of the body (wrist, neck, and back). The machine measures current in milliamperes (mA). The pretreatment experimental group in the study had an average threshold of pain (pain was first detectable) at µ = 3.15mA with standard deviation = 1.45mA. Assume that the distribution of threshold pain, measured in milliamperes, is symmetrical and more or less mound-shaped. Use the empirical rule to
(a) estimate a range of milliamperes centered about the mean in which about 68% of the experimental group had a threshold of pain.
(b) estimate a range of milliamperes centered about the mean in which about 95% of the experimental group had a threshold of pain.