Evaluating the reliability of a revised two-step assessment of sex and gender in adolescents and adults

This study assessed the reliability of an updated two-step measure of gender and sex. Gender diverse youths (<i>n</i> = 610, <i>Mean</i> _age = 15 years, <i>SD</i> = 2) and their parents (<i>n</i> = 606, <i>M</i> _age = 48, <i>SD</i> = 5) completed a measure of sex and gender twice with a time delay of 30-60 minutes. Reliability was high, with 95% or higher agreement for sex and gender for both parents and youths. Reliability was highest for parents and for cisgender and transgender boys and girls, slightly lower for nonbinary youths, and lowest for youths who selected other options (e.g., "I don't know"). The two-step measure showed high levels of convergent validity as well. Results demonstrate that the two-step assessment with updated response options reliably identified participants' sex and gender, and these responses could be combined to classify gender modality, including to identify transgender individuals.