A Note on Good Model Fit

Model fit is based on how close the model-implied covariance matrix is to the observed covariance matrix

Some details:

The confirmatory fit index (CFI) is calculated as:


where subscript 0 implies the null model, and subscript 1 implies the proposed model. 

The Tucker Lewis index (TLI), also known as the non-normed fit index, is calculated as:


The Root mean squared error of approximation (RMSEA) is calculated as: