In the Fit Model platform, the Effect Tests table displays "Missing degrees of freedom", and the Parameter Estimates table displays messages such as "Biased" and "Fixed to zero". Why are these messages displayed?These messages indicate that you have linear dependence (a linear combination of one or more factors that can accurately represent the value of another factor). Use the Singularity Details report to determine which factors are linearly dependent, and consider how you might adjust your model to remove the dependence.
FAQ # 1231
