Factor loading is the measure of the correlation between the observed variable and the factor. It is used to determine the strength of the association between the observed variable and the factor in factor analysis. In factor analysis, factor loadings are used to determine how much the observed variables are associated with the latent variables or factors.

Factor loading is calculated by the Pearson correlation coefficient between the observed variable and the factor. It is a numerical value that ranges from -1 to +1. A factor loading of +1 indicates that the observed variable is perfectly correlated with the factor, while a factor loading of -1 indicates that the observed variable is perfectly inversely correlated with the factor. A factor loading of 0 indicates that the observed variable is not associated with the factor.

The factor loading is used to determine which variables are associated with which factors. A high factor loading indicates that the observed variable is strongly associated with the factor, while a low factor loading indicates that the observed variable is weakly associated with the factor. Variables with high factor loadings are retained in the factor analysis, while variables with low factor loadings are dropped from the analysis.