Torsion during hip external rotation (ER) and extension may be responsible for certain kinds of injuries in golfers and other athletes. The article “Hip Rotational Velocities During the Full Golf Swing” (J. of Sports Science and Medicine, 2009: 296–299) reported on a study in which peak ER velocity and peak IR (internal rotation) velocity (both in deg.sec−1) were determined for a sample of 15 female collegiate golfers during their swings. The following data was supplied by the article’s authors
Golfer | ER | IR | cliff | Z perc |
1 | -130.6 | -98.9 | -31.7 | -1.28 |
2 | -125.1 | -115.9 | -9.2 | -0.97 |
3 | -51.7 | -161.6 | 109.9 | 0.34 |
4 | -179.7 | -196.9 | 17.2 | -0.73 |
5 | -130.5 | -170.7 | 40.2 | -0.34 |
6 | -101.0 | -274.9 | 173.9 | 0.97 |
7 | -24.4 | -275.0 | 250.6 | 1.83 |
8 | -231.1 | -275.7 | 44.6 | -0.17 |
9 | -186.8 | -214.6 | 27.8 | -0.52 |
10 | -58.5 | -117.8 | 59.3 | 0.00 |
11 | -219.3 | -326.7 | 107.4 | 0.17 |
12 | -113.1 | -272.9 | 159.8 | 0.73 |
13 | -244.3 | -429.1 | 184.8 | 1.28 |
14 | -184.4 | -140.6 | -43.8 | -1.83 |
15 | -199.2 | -345.6 | 146.4 | 0.52 |
a. Is it plausible that the differences came from a
b. The article reported that
c. The article stated that “The lead hip peak IR velocity was significantly greater than the trail hip ER velocity (p = 0.003, t value = 3.65).” (The phrasing suggests that an upper-tailed test was used.) Is that in fact the case? [Note: “p = .033” in Table 2 of the article is erroneous.]
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Chapter 9 Solutions
Probability and Statistics for Engineering and the Sciences