Psychometric properties of the Global Operative Assessment of Laparoscopic Skills (GOALS) using item response theory

BACKGROUND: The extent to which each item assessed using the Global Operative Assessment of Laparoscopic Skills (GOALS) contributes to the total score remains unknown. The purpose of this study was to evaluate the level of difficulty and discriminative ability of each of the 5 GOALS items using item response theory (IRT). METHODS: A total of 396 GOALS assessments for a variety of laparoscopic procedures over a 12-year time period were included. Threshold parameters of item difficulty and discrimination power were estimated for each item using IRT. RESULTS: The higher slope parameters seen with "bimanual dexterity" and "efficiency" are indicative of greater discriminative ability than "depth perception", "tissue handling", and "autonomy". CONCLUSIONS: IRT psychometric analysis indicates that the 5 GOALS items do not demonstrate uniform difficulty and discriminative power, suggesting that they should not be scored equally. "Bimanual dexterity" and "efficiency" seem to have stronger discrimination. Weighted scores based on these findings could improve the accuracy of assessing individual laparoscopic skills.