The development and validation of a short form of the STERLinG: a practical, valid and reliable tool to evaluate teacher competencies to encourage reflective learning.

Background: To optimize response rates, it is important to have brief, comprehensive instruments.

Aims: We have developed and validated a short form of an instrument for measuring students' perceptions of teachers' competencies to encourage students' reflective learning in small groups (the STERLinG).

Methods: Based on statistical and content criteria, the original 36-item STERLinG was reduced to 15 items: three scales with five items each. This mini-STERLinG was validated. Confirmatory factor analysis was performed and internal consistencies were calculated.

Results: The instrument was completed by 501 respondents (63%). The original instrument structure was confirmed with 62.6% explained variance. Reliabilities were high with 0.91 for the entire mini-STERLinG and 0.87, 0.85 and 0.81 for its subscales.

Conclusions: The mini-STERLinG was found to be a feasible, valid and reliable instrument.