Alfa de Cronbach es un coeficiente que sirve para medir la fiabilidad de una escala de medida, y cuya denominación Alfa fue realizada por Cronbach en 1951.
El alfa de Cronbach es una media de las correlaciones entre las variables que forman parte de la escala. Puede calcularse de dos formas: a partir de las varianzas (alfa de Cronbach) o de las correlaciones de los ítems (Alfa de Cronbach estandarizado).
The alpha coefficient can be used as an index of internal robustness. But it does not imply anything about stability in time or about equivalence between alternate forms of the instrument.
- The alpha coefficient can be displayed as the lower limit of the reliability coefficient known as the precision coefficient. In other words, an alpha coefficient of 0.80 only implies that the precision coefficient is greater than 0.80, but it is not known by how much it differs.
- The alpha coefficient can be visualized as the average of all the reliability coefficients obtained by the two halves methods.
- The alpha coefficient is not an index of one-dimensionality of the instrument.
- The alpha coefficient can be used in any situation in which you want to estimate the reliability of a compound.
There are factors that can affect reliability, such as:
- Homogeneity of the group.
- Weather.
- Size of the questionnaire.
- Objectivity of the process of assigning scores.
