The expert players In the maximum velocity task:

Table 4 tells us about the predictor variables and the methods used. It shows us the order in which the variables were entered and removed. We can see that in this case eleven variables were added (e.g., the upper arm velocity (Y) as a predictor variable was added in the first step, hand velocity (X) was added in the second step, upper arm velocity (X) as a predictor variable was added in the third step, hand velocity (Y) as a predictor variable was added in the fourth step, lower arm velocity (Y) as a predictor variable was added in the fifth step, lower arm velocity (Z) as a predictor variable was added in the sixth step, bat velocity (Y) as a predictor variable was added in the seventh step, bat velocity (Z) as a predictor variable was added in the eight step, hand velocity (Z) as a predictor variable was added in the ninth step, lower arm velocity (X) as a predictor variable was added in the tenth step, and finally bat velocity (X) as a predictor variable was added in the final step). However, one variable (upper arm velocity on the Z-axis) was removed, because it did not significantly strengthen the model when I selected the stepwise method.

Table 5 is important. Here SPSS reports R, R², and Adjusted R². Multiple R is the correlation coefficient between the observed and predicted values. R square (R²) is the proportion of the variability in the dependent variable that is attributable to the regression equation. It is the square of multiple R. Adjusted R² corrects for R² being an overly optimistic estimate of how well the model fits the population and decreases R² accordingly.

In Table 5 we can see that model 11 accounts for 52.5% of the variance in performance accuracy (Adjusted R²= .525).

92.342 11 8.395 70.694 .000^k

Predictors: (Constant), velocity upper Y, velocity hand X, velocity upper X, velocity hand Y, velocity lower Y, velocity lower Z, velocity bat Y, velocity bat Z, velocity hand Z, velocity lower X, velocity bat X.

k.

Table 4. Variables Entered / Removed in the Velocity Segments in the maximum velocity trials of the expert players.

Table 5.Summary of model of the velocity biomechanical variable entered into the model of the maximum velocity of the expert players.

Predictors: (Constant), velocity upper Y, velocity hand X, velocity upper X, velocity hand Y, velocity lower Y, velocity lower Z, velocity bat Y, velocity bat Z, velocity hand Z, velocity lower X, velocity bat X k.

Table 6 reports an ANOVA, which assesses the overall significance of my model. As p< .001 the model is significant; as can be seen in Table 6, the ANOVA results for the eleven models, they are significant.

Table 6. Analysis-of-variance table of the velocity biomechanical variable entered into the model of the maximum velocity of the expert players.

Table 7 illustrates the unstandardized and standardized coefficients for the variables included in the model. This table gives information for the predictor variables that are included in the

model. Based on the coefficients in this table, the resulting regression equation is:

Performance accuracy= .967+ (.860 x velocity upper arm Y) + (.046 x velocity hand X) - (.378 x velocity upper arm X) + (.244 x velocity hand Y) - (.206 x velocity lower arm Y) + (.133 x velocity lower arm Z) - (.099 x velocity bat Y) + (.125 x velocity bat Z) - (.130 x velocity hand Z) + (.111 x velocity lower arm X) + (.037 x velocity bat X).

Table 7. The unstandardized and standardized regression coefficients of the velocity biomechanical variable entered into the model of the maximum velocity of the expert players.

.967 .035 27.672 .000

Figure 26. The mean velocities of the maximum velocity trials of the expert players.

Model Summary

Predictors: (Constant), velocity hand Y, velocity lower X, velocity upper X, velocity bat Y, velocity bat Z, velocity lower Z, velocity upper Z, velocity bat X, velocity hand Z

k.

Table 8 tells us about the predictor variables and the methods used. It shows us the order in which the variables were entered and removed. We can see that in this case nine variables were added (e.g., hand velocity (Y) as a predictor variable was added in the first step, lower arm velocity (X) was added in the second step, upper arm velocity (X) as a predictor variable was added in the third step, bat velocity (Y) as a predictor variable was added in the fourth step, bat velocity (Z) as a predictor variable was added in the fifth step, lower arm velocity (Z) as a predictor variable was added in the sixth step, upper arm velocity (Z) as a predictor variable was added in the seventh step, bat velocity (X) as a predictor variable was added in the eighth step¸ and finally hand velocity (Z) as a predictor variable was added in the final step). In addition, three variables (upper arm velocity (Y), lower arm velocity (Y), and hand velocity (X)) were removed, because they did not significantly strengthen the model when I selected the stepwise method.

In Table 9 we can see that model 9 accounts for 23% of the variance in performance accuracy (Adjusted R²= .230).

Table 8. Variables entered / Removed of the velocity biomechanical variable entered into the model of the technique of the expert players.

Table 9. Summary of model of the velocity biomechanical variable entered into the model of the technique of the expert players.

37.776 9 4.197 21.781 .000ⁱ

Predictors: (Constant), velocity hand Y, velocity lower X, velocity upper X, velocity upper Y, velocity bat Y, velocity bat Z, velocity lowerZ, velocity upper Z, velocity bat X i.

Table 10. Analysis-of-variance table of the velocity biomechanical variable entered into the model of the technique of the expert players.

Table 11 illustrates the unstandardized and standardized coefficients for the variables included in the model. This table gives information for the predictor variables that are included in the model. Based on the coefficients in this table, the resulting regression equation is:

Performance accuracy= 3.62- (.152 x velocity hand Y) + (.179 x velocity lower arm X) - (.798 x velocity upper arm X) + (.050 x velocity bat Y) - (.134 x velocity bat Z) + (.789 x velocity lower arm Z) - (.815 x velocity upper arm Z) - (.063 x velocity bat X) + (.126 x velocity hand Z).

Table 11. The unstandardized and standardized regression coefficients of the velocity biomechanical variable entered into the model of the technique of the expert players.

To sum up, using the stepwise method, a significant model emerged: F (9, 696) = 21.78, P<.000. The model explains 23% of the variance in performance accuracy (Adjusted R² = .230). Figure 27 shows the mean velocities of the technique trial of the expert players.

Figure 27. The mean velocities of the technique trial of the expert players.

4.3.2.1.2 The novice players