## 3 Results  
Table 4 shows that all the analyzed population groups present significant differences (\(p\) < 0.05) between the observed and expected proportions for each group, except for the female elite group [F-E] (\(p\) = 0.133). The most significant effect is observed for the male elite group [M-E] (V = 0.21), while the smallest effect is found in the Total Federated group [TF] (V = 0.06), regardless of sex (V\({}_{\text{TF-F}}\) = V\({}_{\text{TF-M}}\) = 0.07). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Population Group** & **Q1 (\%)** & **Q2 (\%)** & **Q3 (\%)** & **Q4 (\%)** & \(\chi\)**2** & \(p\)** & **V** \\ \hline Total Federated & 25.88 & 26.02 & 24.61 & 23.49 & 143.187 & \textless{}0.001 & 0.06 \\ TF-F & 25.63 & 26.34 & 23.72 & 24.32 & 57.351 & \textless{}0.001 & 0.07 \\ TF-M & 26.02 & 25.84 & 25.11 & 23.03 & 98.244 & \textless{}0.001 & 0.07 \\ Youths & 26.96 & 27.55 & 22.85 & 22.64 & 121.514 & \textless{}0.001 & 0.12 \\ F-Y & 27.47 & 27.07 & 21.44 & 24.02 & 57.468 & \textless{}0.001 & 0.12 \\ M-Y & 26.60 & 27.89 & 23.84 & 21.68 & 74.826 & \textless{}0.001 & 0.12 \\ Elite & 27.87 & 26.73 & 20.03 & 25.37 & 29.535 & \textless{}0.001 & 0.15 \\ F-E & 22.69 & 28.65 & 23.65 & 25.00 & 5.599 & 0.133 & 0.10 \\ M-E & 30.92 & 25.59 & 17.89 & 25.59 & 38.516 & \textless{}0.001 & 0.21 \\ \hline \hline \end{tabular} Note: Total Federated includes all categories of the SOL, for both female (TF-F) and male (TF-M) athletes. The youth subgroup includes the U-10 category (mixed), F-Y categories (F-12, F-14, F-16, F-18, F-20), and M-Y categories (M-12, M-14, M-16, M-18, M-20). Additionally, the elite subgroup consist of the elite female (F-E) and male (M-E) categories. Qi = born in the first quarter of the year (January–March); Q2 = born in the second quarter of the year (April–June); Q3 = born in the third quarter of the year (July–September); Q4 = born in the fourth quarter of the year (October–December).  
\end{table} 
Table 4: Results of the Chi-square test (\(\chi\)2), significance values (\(p\)), and effect size (Cramer’s V) for the different population groups analyzed in relation to the quarterly distribution of births (Q): \(\chi\)2 (critical) = 7.8147 (\(p\) = 0.05). The bar charts for the distribution (%) by birth semester of the different populations and subgroups studied, shown in Figure 1, indicate an overrepresentation of athletes born in the first semester (S1) compared to those born in the second semester (S2) for all populations and subgroups, regardless of sex, except for the female sample of the elite subgroup. Statistically significant differences between those born in S1 and those born in S2 are observed in all cases except for the previously mentioned female elite subgroup. The [PERSON]'s V values obtained (0.07-0.16) indicate a small effect, which is practically identical to those obtained for the quartile distribution, also showing a small effect size. Table 5 shows that most of the analyzed age groups present significant differences (\(p<0.05\)) in the birth distribution across quartiles. Only two age groups, M-16 (\(p=0.112\)) and F-Elite (\(p=0.133\)), do not show significant differences. Regarding effect size (Cramer's V), the age groups with the most significant effects are the M-Elite (V = 0.21) and the U-10 category (V = 0.19), although the effect is moderate. In the remaining age groups, the effect magnitude is small-to-medium (V values between 0.12 and 0.16). The bar charts for the birth semester distribution in Figure 2 (U-10 category and female categories) and Figure 3 (male categories) reflect a classic relative age effect with an overrepresentation of athletes born in Q1 and Q2 (first semester, S1) and an underrepresentation of athletes born in Q3 and Q4 (second semester, S2). As shown in the data of both figures, the only age group that does not present significant differences between birth semesters is the female elite category. The Cramer's V values obtained (0.07-0.16) indicate a small effect.