# Born to Win? The Hidden Bias of Birthdates in Spanish Orienteering Talent Selection
## 3 Results  
The results presented in Table 3 indicate a statistically significant association between birth quartile and selection to represent Spain in international competitions, exclusively within the male JWOC category (\(\chi^{2}\) (3) = 8.13; \(p\) = 0.043). Furthermore, this group exhibited the largest effect size among all competitions and competitive groups studied (\(V\) = 0.34). For the remaining events and categories, although medium effect sizes were observed (\(V\) ranging from 0.20 to 0.23), the association between birth quartile and selection for these championships did not reach statistical significance (\(p>0.05\)). The smallest effect was observed in the female EYOC group (\(V\) = 0.11, small-to-medium association). In contrast to the JWOC male group, no statistically significant RAE was observed in the female sample when analysing birth quartile distribution across all competitions (e.g., EYOC: \(\chi^{2}\)(3) = 0.86, \(p\) = 0.834; JWOC: \(\chi^{2}\)(3) = 2.01, \(p\) = 0.570; WOC + EOC: \(\chi^{2}\)(3) = 2.17, \(p\) = 0.537). Similarly, no significant effect was found for semester distribution (e.g., EYOC: \(\chi^{2}\)(1) = 0.06, \(p\) = 0.867; JWOC: \(\chi^{2}\)(1) = 0.18, \(p\) = 0.822; WOC + EOC: \(\chi^{2}\)(1) = 1.27, \(p\) = 0.259). While no statistical significance was reached, a qualitative examination of the female distribution revealed a less pronounced pattern of RAE compared to males, with effect sizes (Cramer's V) generally lower across all female categories. Although there was an apparent overrepresentation of athletes born in the first half of the year (S1) across all events--especially among male athletes--chi-square analysis by semester (Table 4) revealed no statistically significant associations (\(p>0.05\)). Effect sizes (Cramer's V), although following a similar pattern to that observed for quartiles, were slightly lower. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Event** & **Competitive Group** & **Q1** & **Q2** & **Q3** & **Q4** & \(\chi^{2}\) & \(p\) & \(V\) \\ \hline \multirow{3}{*}{EYOC} & Female & 22 & 18 & 17 & 15 & 0.86 & 0.834 & 0.11 \\  & Male & 32 & 23 & 16 & 18 & 4.54 & 0.209 & 0.23 \\ \multirow{3}{*}{JWOC} & Female & 8 & 13 & 10 & 9 & 2.01 & 0.570 & 0.22 \\  & Male & 29 & 17 & 11 & 14 & 8.13 & 0.043 & 0.34 \\ \multirow{3}{*}{WOC + EOC} & Female & 12 & 16 & 7 & 12 & 2.17 & 0.537 & 0.22 \\  & Male & 25 & 18 & 9 & 13 & 2.70 & 0.441 & 0.20 \\ \hline \end{tabular} Note. EYOC = European Youth Orienteering Championships; JWOC = Junior World Orienteering Championships; EOC = European Orienteering Championships; WOC = World Orienteering Championships. Q1 = born in January–March; Q2 = April–June; Q3 = July–September; Q4 = October–December.  
\end{table} 
Table 3: Chi-square test results by birth quartiles (Q1–Q4) for the different international competitions, stratified by competitive group. \(\chi^{2}\) (critical) (3) = 7.8147 (\(p\) = 0.05). As shown in Figure 1, male athletes born in Q1 were most represented across all international competitions. In the EYOC, athletes born in Q1 significantly outnumbered those in Q3 (\(Z\) = 2.702; \(p\) = 0.007) and Q4 (\(Z\) = 2.335; \(p\) = 0.020). In JWOC, statistically significant differences were found between Q1 and all other quartiles--Q1 vs. Q2 (\(Z\) = 2.152; \(p\) = 0.031); Q1 vs. Q3 (\(Z\) = 3.358; \(p\) = 0.001); Q1 vs. Q4 (\(Z\) = 2.740; \(p\) = 0.006). Similarly, in senior-level events (WOC + EOC), athletes born in Q1 differed significantly from those born in Q3 (\(Z\) = 3.193; \(p\) = 0.001) and Q4 (\(Z\) = 2.314; \(p\) = 0.021). In the female sample (Figure 2), the participation frequency in EYOC followed the typical RAE pattern, with a decreasing distribution from Q1 to Q4 (Q1 \(>\) Q2 \(>\) Q3 \(>\) Q4), although no statistically significant differences were found between quartiles. In other competitions, the only significant difference was between Q2 and Q3 (\(Z\) = 2.159; \(p\) = 0.031) in the senior-level events (WOC + EOC).