The validity of the axial rotation system as a means to objectively evaluate the difficulty of selected trampoline skills
Bollinger, Robert F.
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It was the purpose of this study to determine the validity of the axial rotation system as a means to objectively evaluate the difficulty of selected trampoline skills. The axial rotation system was introduced as an objective tool of measurement to evaluate the difficulty of any individual trampoline skill. Illustrations were provided in the study to indicate how the difficulty of any individual trampoline skill might be determined. It was shown how this determination is based upon a mathematical formula concerning the type and quantity of body axial rotation involved, and the types of landing and takeoff positions required of the skill. Trampoline skills used in this study were selected as a result of pilot study research conducted by the writer. A total of fifty-six skills evolved from this study and were determined to be the most frequently seen trampoline skills in American competition. Questionnaire forms were constructed which gave a random listing of the fifty-six trampoline skills. No indication was given concerning the difficulty of these skills. Axial rotation values for each of the fifty-six skills were established but were not included in the questionnaire. Sixty-five of these questionnaires were sent to two major respondent groups. Thirty-three of the respondents in one group were experienced trampoline coaches and twenty-seven respondents from the other group were experienced trampoline competitors. A total of ninety-seven per cent of the questionnaires sent to these groups was used as a source for raw data. Responses from these groups were used as a criterion measure against the axial rotation system. Pearson Product-Moment coefficients of correlation were sought to test the validity of the axial rotation system against the criterion measure. This was done by sub-dividing the two major respondent groups into five sub groups and establishing correlation coefficients for each of these groups. These coefficients are listed as follows: 1. Group I (All Coaches) Coefficient was: .974 2. Group II (All Male Competitors) Coefficient was: .981 3. Group III (All Female Competitors) Coefficient was: .980 4. Group IV (All Competitors) Coefficient was: .986 5. Group V (All Respondents) Coefficient was: .982 It was found that all five coefficients of correlation were significant beyond the .01 level. Comparisons were made between group means and established axial rotation values for the fifty-six skills as an item analysis. Agreements and disagreements in numerical rating were found to exist between group means and established axial rotation values for some skills. Agreement between the five respondent groups and the axial rotation system was found to be generally high. The average disagreement between the axial rotation system and the group mean for all of the respondents (Group V) was .019 for all skills collectively. In one instance, however, a disagreement on the rating of one skill category was found to exist. This skill category includes three stunts and is commonly referred to as: 'Front Cody Somersaults. Respondents in Group V tended to rate these skills higher than the values established for them in the axial rotation system. Based upon the results of this study, it was concluded that the axial rotation system is an objective method of measuring the difficulty of fifty-three of the skills used in this study. It was also concluded that the axial rotation system did not objectively measure the three skills listed as 'Front Cody Somersaults.' It was further concluded that an adjustment in the axial rotation values should be made to accomodate this category of skills.