DIFFERENCES BETWEEN GENDER AND BIRTH MONTH ON THE GRADES OF SECONDARY EDUCATION STUDENTS

The month of birth could influence the performance of adolescents in different areas, such as the school. Although born in the same year, inside a classroom there are students older than others, and this could result in certain advantages. This is known as the relative age effect. This study aimed to analyze the relative age effect on the academic grades of students of Spanish Secondary Education. 315 subjects (158 females and 157 males) from one high school in Valencia (Spain) with a mean age of 14.43 ± 1.42 years, voluntarily participated in the study; repeaters were excluded ex-post. The academic record of each student was accessed to obtain the year mean grades between 0 and 10. The month of birth was obtained through a self-reported online questionnaire and classified into homogeneous quartiles and halves. A two-way analysis of variance (ANOVA) with the gender and the relative age as the between-subject factors was conducted to assess differences between the study variables. A significant effect of the gender (F = 9.77, p = .02, ηp2 =.03) and a tendency of the birth month divided into quartiles (F = 2.47, p = .06, ηp2 = .02) were found. No significant effect of the interaction gender*birth month (quartiles) was observed (F = .22, p > .05). There were significant differences when the relative age was divided into halves (F = 4.41, p = .04, ηp2 = .01). Better academic performance was observed in women compared to men (mean difference [m.d.] .57, 95% confidence interval [CI] [.21 - .93]) and in the students born in the first half of the year (m.d. .38, 95%CI [.36 - .40]. The students born in the second quartile of the year (April to June) obtained the best grades, showing significant differences only with the students in the third quartile (July to September). The results of this study suggest that the month of birth and gender are factors influencing the academic performance of students, although the effect sizes were small. Teachers and policymakers should be aware of this effect and consider the month of birth and gender in the design of strategies to academic success and ensure equal opportunities for all the students.