Rasch model

Physics

Engineering

Developmental psychology

Surgery

Civil engineering

Psychology

Power (physics)

Psychometrics

Physical therapy

Intra-rater reliability

Grading (engineering)

Scale (ratio)

Buttocks

Grading scale

Reliability (semiconductor)

Inter-rater reliability

Quantum mechanics

Validity

Clinical psychology

Medicine

Rating scale

Plastic & Reconstructive Surgery

Background: New treatment methods to improve and enhance the appearance of the buttocks require globally accepted scales for aesthetic research and patient evaluation. The purpose of this study was to develop a set of grading scales for objective assessment of the gluteal region and assess their reliability and validity. Methods: Twelve photonumeric grading scales were created. Eleven aesthetic experts rated photographs of 650 women in two validation sessions. Responses were analyzed to assess interrater and intrarater reliability. The Rasch model was used as part of the validation process. Results: All the scales exceeded criteria for acceptability, reliability, and validity. Overall interrater reliability and intrarater reliability were both “almost perfect” ( p = 0.15 and p = 0.16, respectively). Conclusion: Consistent outcomes between raters and by individual raters at two time points confirm the reliability of the Objective Buttocks Assessment Scale in female patients and suggest it will be a valuable tool for use in research and clinical practice.

The Objective Buttocks Assessment Scale: A New and Complete Method to Assess the Gluteal Region