Stabilizing the measurement of relationship instability: Identifying optimal number of response options and a single-item assessment

Participant reports of romantic relationship instability are of central interest in relationship science. However, this construct is inconsistently measured, with different response options and items presented. Across two studies, we assessed the psychometric properties of a 6-item scale of relationship instability based on a 2- or 5-response option (RO) format ( N Study 1 = 853; N Study 2 = 1,007). We also examined the psychometric properties of each item to identify a strong single-item measure of relationship instability. In both studies, mean differences in item scores, total scores, reliability, and response time based on response option set were present, and data from the 5-RO condition displayed greater variability. A single-item assessment with strong psychometric qualities and minimal reductions in convergent validity is recommended for future use.