## 3 Results
### The Validity of the Test  
There were no significant differences (\(p>0.05\)) between the My Jump 2 app and Optojump for all jumps in male participants with trivial effects size (from \(-0.03\) to \(-0.09\)) (Table 4). Very large correlations were observed between the My Jump 2 app and Optojump for SJ (r = 0.95, \(p=0.001\)), CMJ (r = 0.98, \(p=0.001\)), and CMJAS (r = 0.98, \(p=0.001\)). Similar results were obtained for female recreationally active adults (Table 5). No significant differences (\(p>0.05\)) were observed between the My Jump 2 app and Optojump for all jumps in female recreational athletes with trivial effects size (from \(-0.09\) to \(-0.19\)). Very large correlations were observed between the My Jump 2 app and Optojump for all jumps (r \(>0.94\), \(p=0.001\)). Figures 2-4 show the level of agreement for all jumps. [PERSON] and [PERSON]'s plot depicting limits of agreement for SJ height between the Optojump and My Jump 2 show that the majority of data points are within the 95% CI's (Figure 2). Further analysis of the Bland-Altman plots in male athletes revealed very low R\({}^{2}\) values (R\({}^{2}\leq 0.10\)), meaning outcomes estimated from My Jump 2 had no predisposition to overestimate or underestimate jump performance. On the contrary, in female participants, the plot shows bias related to the magnitude of jump height (R\({}^{2}\) = 0.74), such that, at lower jump heights, values derived from Optojump data tended to be higher than those from My Jump 2, resulting in positive difference scores. Moreover, the mean bias between the two methods for all jumps was 0.51 cm. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **My Jump 2** & **Optojump** & **Diff. (95\% CI)** & **ES** & **r (95\% CI)** & **Rating** \\ \hline
**SJ** & \(29.6\pm 6.0\) & \(30.0\pm 6.3\) & \(0.40\) (\(-3.26\); \(2.46\)) & \(-0.07\) & \(0.95\) (\(0.91\); \(0.97\)) & Very large \\
**CMJ** & \(31.9\pm 6.6\) & \(32.5\pm 7.1\) & \(0.60\) (\(-3.79\); \(2.59\)) & \(-0.09\) & \(0.98\) (\(0.95\);\(0.99\)) & Very large \\
**CMJAS** & \(39.4\pm 9.7\) & \(39.7\pm 9.5\) & \(0.30\) (\(-4.76\); \(4.16\)) & \(-0.03\) & \(0.98\) (\(0.97\);\(0.99\)) & Very large \\ \hline \hline \end{tabular} Abbreviations: r, Pearson’s correlation coefficient.  
\end{table} 
Table 4: Descriptive statistics and validity analysis in male recreationally active adults based on Pearson’s r. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **SJ** & **CMJ** & **CMJAS** \\ \hline
**Test (cm)** & \(23.9\pm 6.0\) & \(26.8\pm 6.3\) & \(29.3\pm 6.0\) \\
**Retest (cm)** & \(25.8\pm 6.8\) & \(27.3\pm 6.2\) & \(30.2\pm 6.4\) \\
**ES** & \(0.30\) (small) & \(0.08\) (trivial) & \(0.15\) (trivial) \\
**Diff (95\% CI)** & \(1.90\) (\(1.2\)) & \(0.5\) (\(-0.1\); \(1.1\)) & \(0.9\) (\(0.2\); \(1.6\)) \\
**ICC (95\% CI)** & \(0.94\) (\(0.86\); \(0.97\)) & \(0.97\) (\(0.93\); \(0.98\)) & \(0.97\) (\(0.92\); \(0.98\)) \\
**TE (95\% CI)** & \(1.6\) (\(1.3\); \(2.3\)) & \(1.1\) (\(0.8\); \(1.5\)) & \(1.2\) (\(0.9\); \(1.6\)) \\
**CV\% (95\% CI)** & \(7.2\) (\(5.6\); \(10.3\)) & \(4.3\) (\(3.4\); \(6.1\)) & \(4.3\) (\(3.3\); \(6.0\)) \\
**SWC**\% & \(1.3\) (\(5.1\%\)) & \(1.2\) (\(4.5\%\)) & \(1.2\) (\(4.2\%\)) \\
**Rating** & marginal & good & OK \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Test-retest reliability and usefulness of My Jump 2 in female recreationally active adults. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **My Jump 2** & **Optojump** & **Diff. (95\% CI)** & **ES** & **r (95\% CI)** & **Rating** \\ \hline
**SJ** & \(29.6\pm 6.0\) & \(30.0\pm 6.3\) & \(0.40\) (\(-3.26\); \(2.46\)) & \(-0.07\) & \(0.95\) (\(0.91\); \(0.97\)) & Very large \\
**CMJ** & \(31.9\pm 6.6\) & \(32.5\pm 7.1\) & \(0.60\) (\(-3.79\); \(2.59\)) & \(-0.09\) & \(0.98\) (\(0.95\);\(0.99\)) & Very large \\
**CMJAS** & \(39.4\pm 9.7\) & \(39.7\pm 9.5\) & \(0.30\) (\(-4.76\); \(4.16\)) & \(-0.03\) & \(0.98\) (\(0.97\);\(0.99\)) & Very large \\ \hline \hline \end{tabular} Abbreviations: r, Pearson’s correlation coefficient.  
\end{table}