Question

An article in Medicine and Science in Sports and Exercise “Electrostimulation Training Effects on the Physical Performance of Ice Hockey Players,” (2005, Vol. 37, pp. 455–460) considered the use of electromyostimulation (EMS) as a method to train healthy skeletal muscle. EMS sessions consisted of 30 contractions (four-second duration, 85 Hz) and were carried out three times per week for three weeks on 17 ice hockey players. The ten-meter skating performance test showed a standard deviation of 0.09 seconds. Construct a 90% confidence interval of the standard deviation of the skating performance test. Assume population is approximately normally distributed. Round your answers to 3 decimal places.

Answer 1

df = n - 1 = 17 - 1 = 16

chi-square critical values at 0.10 significance level with 16 df = L = 7.962 , U = 26.296

90% confidence interval for is

sqrt [ ( n - 1) S² /  U ] < < sqrt [ ( n - 1) S² /  L ]

sqrt [ 16 * 0.09² / 26.296 ] < < sqrt [ 16 * 0.09² / 7.962 ]

0.070 < < 0.128

90% CI is ( 0.070 , 0.128 )