validity and reliability of a self-report likert-type measure of nightmare frequency

Background and objective: nightmare frequency is typically measured using interval and ordinal, but rarely likert-type, scales. the current study aimed to examine the validity and reliability of a likert-type measure of retrospective nightmare frequency.materials and methods: participants included a convenience sample of undergraduate students. they completed a recent-ly developed likert-type nightmare frequency item, an established nightmare frequency scale, an estimate of nightmare frequency over the past week, and measures of hypothetically related variables including neuroticism, psychological dis-tress, and trauma symptoms. convergent and discriminant validity was evaluated through relationships between the likert-type nightmare frequency item with other nightmare measures and hypothetically related variables. reliability was esti-mated using a correction for attenuation approach designed to provide a conservative estimate of single-item reliability.results: the sample included 233 (119 female, 51.1%; 114 male, 48.9%) university students (mean age: 19.05 ± 1.91). the average convergent validity coefficient between the likert-type nightmare frequency item and other nightmare measures (r = 0.647) was significantly different (z = 5.45, p < 0.001) from its average correlation coefficient with hypo-thetically related measures (r = 0.256). the single-item reliability coefficient was 0.722.conclusion: the reliability and convergent and discriminant validity of the likert-type nightmare frequency item were supported.