2.1. Research Data
In this study, the adequacy of akick impact standard by weight class was confirmed using 2018 Jakarta Asian Games Taekwondo match data. Specifically, there werea total of 104 matches (under-58kg weight class: 24 matches, under-63kgweight class: 25 matches, under-68kgweight class: 21 matches, under-80kgweight class: 20 matches, and over-87kgweight class: 14 matches), with a maximum of 26 countries and a minimum of 21 countries. For women's matches, there werea total of 84 matches (under-49kgweight class: 16 matches, under-53kgweight class: 17 matches, under-57kgweight class: 19 matches, under-67kgweight class: 15 matches, over-67kgweight class: 17 matches), with a maximum of 26 countries and a minimum of 15 countries(table 1).
Table 1. Taekwondo Men's and Women's matchesby weight class and participating country
|
Men's
|
Women's
|
Weight Class
|
Number of games(%)
|
Number of Participating Countries
|
Weight Class
|
Number of games(%)
|
Number of Participating Countries
|
Under58kg
|
24(23.1)
|
26
|
Under 49kg
|
16(19.1)
|
17
|
Under63kg
|
25(24.0)
|
26
|
Under 53kg
|
17(20.2)
|
18
|
Under68kg
|
21(20.2)
|
22
|
Under 57kg
|
19(22.6)
|
20
|
Under 80kg
|
20(19.2)
|
21
|
Under 67kg
|
15(17.9)
|
16
|
Over 80kg
|
14(13.5)
|
21
|
Over 67kg
|
17(20.2)
|
15
|
Total
|
104(100)
|
|
Total
|
84(100)
|
|
2.2. DataAcquisition Procedure
In this study, data from KP&P PSSobtainedin the 2018 Jakarta Asian Games Taekwondo matcheswere provided by the Asian Taekwondo Federation and KP&P. This is a score that can be publicly confirmed as the PSS score generated in the game. The KP&P PSS is an official accreditation body certified by the WTF (October 23, 2012) and it is the official scoring system used in world competitions and Asian Games.
Only the scoring impact generated in the trunk area was entered and classified by weight classin order to use the data forthe scoring impact calculated by KP &PPSS as research data. Data was input by threeTaekwondo match analysis experts to minimize error. Several matches were randomly selected and re-recorded to confirm the match with the previous record,after enteringthe data. The PSS kicking impact calculated through this process was 2,286 times for men (scoring frequency: 814 times, effective hit frequency: 1430), and 1,389 times for women(scoring frequency: 650 times, effective hit frequency: 688 times), and these values were used as research data.
2.3. Group Classification for Establishing Kick Impact Reference Pointsfor the Protector and Scoring System
Thecriterion groups model, one of the empirical methods, was usedin this studyto confirm the adequacy of the Taekwondo PSS kick impact reference point. The reference group model is divided into the group that meets the criteria and the onthat does not. The intersection point of the distribution of scores of the two groups was set as the reference point (Popham, 1990). Therefore, twomethods were used in this study to classify the group to determine the appropriateness of the kick impact reference. First, the winning group (which met the criteria) and the non-winning group (which did not meet the criteria), according to weight category, were divided and compared with the reference point shown at the intersection point of the 2-group score distributions with the kick impact reference point currently applied by WTF. Then, after classifying the groups according toweight class, the score distribution intersection point was identified. For example, for men's weight classes, the current kick impact reference point is determined by checking and comparing the intersection of the score distributions for the twogroups in the following order: under-58kg, and under-63kg, under-63kg and under-68kg, under-68kg and under-80kg, under-80kg, andover-80kgweight classes.
2.4. Data Processing Method
The descriptive statistics forthe PSS kick scoring impact were calculatedby weight class. Cutoff scores were calculated to establish scoring criteria according to the reference group. The cutoff score was calculated based on the standard normal distribution using the mean and standard deviation of the kicking intensities of the winning and non-winning groups according togender and weight. Furthermore, the intersection of the kicking intensity distributions of the winning and non-winning groups was selected as the cutoff score (Kaftandjieva, 2010). The accuracy of the classification was calculated to verify the validity of the scoring criteria through the cutoff score (Morrow, Mood, Disch, & Kang, 2015). R program (ver 3.6.1) and MS-Excel were used for data analysis.