The present study was aimed to obtain a reduced version of School Coexistence Questionnaire, by using the methodology proposed by Jornet, Gonzalez-Such and Perales (2012 ) for optimizing complex constructs. Describes the results obtained in each of the steps proposed in the methodology for optimizing the measurement of complex constructs (Jornet, Gonzalez-Such and Perales, 2012), resulting from the application of the questionnaire to a sample of 1259 middle-school students in Baja California, Mexico. The methodology is made up of the following six phases: (a) Exploration of the items of the original scale, (b) Missing values analysis and imputation decisions, (c) items’ selection of from its contribution to the reliability of scale, (d) Estimation of the total score of the reduced version, (e) Exploration of the quality of the reduced version, and (f) Reduction and final validation of the micro-instrument. The results highlight the psychometric properties of the short version of the instrument (k = 31) with dimensions of Inclusion (k = 12) Democracy (k = 9) and Peace (k = 10), reported correlations of .938, .932 and .932, with respect to the original dimensions¸ and internal consistency indices and acceptable levels of variance explained.

Measurement, School coexistence, Validity, Reliability, Construct.