An article in Medicine and Science in Sports and Exercise [\"Electrostimulation

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 (4-second duration. 85 Hz) and were carried out three times per week for three weeks on 17 ice hockey players. The 10-meter skating performance test showed a standard deviation of 0.09 seconds. Construct a 95% confidence interval of the standard deviation of the skating performance test.

Explanation / Answer

Since we're not given the standard deviation of the population, but rather of the sample, we must use a T-Interval to calculate the 95% confidence interval as opposed to a Z-Interval. There are 6 degrees of freedom (sample size - 1), so the appropriate t-value for 95% confidence and 6 degrees of freedom is 2.447 (by looking at a table).

The 95% confidence interval can be found by the formula:

315 ± (2.447)/n

Where is the standard deviation of the sample and n is the sample size. This is equivalent to:

315 ± (2.447)(16)/7 = 315 ± 14.80

So the 95% confidence interval for the mean would be (300.2, 329.8)

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.