Usos del coeficiente alfa de Cronbach en el análisis de instrumentos escritos

it was performed a study, to evaluate the precision of a written test by means of a reliability analysis. the test, with 30 questions exploring some kind of professional knowledge, was applied to a set of 45 persons. using the spss for windows version 16 software, a data base was created with the scores obtained. we calculated the cronbach alpha coefficients for different parts of the test and the corresponding indexes of discrimination in order to determine the most relevant variables related with the reliability of the test. the principal findings were presented in statistical tables. a negative value of the reliability coefficient was obtained for the initial test, but, by means of putting out some questions and making appropriate changes in the score scales of them, a new version of the test with a medium level of reliability was obtained. it was concluded that the reliability analysis is an effective tool to increase the precision of a test.