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Table 1 Analysis of the rating scale structure using Linacre’s [23] eight guidelines

From: Psychometric validation of the Laval developmental benchmarks scale for family medicine

Linacre’s (2004) guidelines Result
1. At least 10 observations of each category There were at least 10 observations per response option (54 observations in the first option; 3615 in the second; and 22,023 in the third).
2. Regular observation distribution Distribution of observations across response options was irregular, meaning that option 3 was clearly the most frequent option, followed by option 2, while option 1 was seldom chosen.
3. Average measures advance monotonically with category Average ability estimates advanced monotonically with options going from −1.10 logits (option 1) to 2.77 logits (option 2) and then to 6.59 logits (option 3).
4. Outfit mean-squares less than 2.0 Infit and outfit indices were acceptable, all comprised between .99 and 1.30.
5. Step calibrations advance Step calibrations advanced, indicating no disordered thresholds. The step between option 1 and 2 was estimated at −3.61 logits, and the step between option 2 and 3 was estimated at 3.61 logits.
6. Ratings imply measures, and measures imply ratings Congruence between measures and ratings as well as between ratings and measures was generally good. It varied between 66 and 93% for options 2 and 3. For option 1, the congruence between measures and ratings was acceptable at 55%, but the congruence between ratings and measures was at 11%.
7. Step difficulties advance by at least 1.4 logit The distance of 7.22 logits between the two steps was larger than 1.4 logits.
8. Step difficulties advance by less than 5.0 logits The distance of 7.22 logits between the two steps was larger than 5 logits.