The focus of this study was the invariance of the factor structure of the B
rief Psychiatric Rating Scale (BPRS) over time. An initial sample of 193 in
dividuals diagnosed with nonacute schizophrenia or schizoaffective disorder
were administered the BPRS every 6 months over a 3-year period. Multiple-g
roups confirmatory factor analysis was used to fit the 4-factor oblique mod
el of Mueser, Curran, and McHugo (1997) to both the 16-item and 18-item ver
sion of the BPRS. The results show that. the model was configurally invaria
nt over time, but it was more invariant for the 16-item version. The findin
gs suggest that the factors, Thought Disturbance, Anergia, Affect, and Diso
rganized, as measured by the BPRS are distinct symptom constructs that endu
re over at least a 3-year period,bur the strength of their interrelationshi
ps varies. implications for interpretation of change in observed scores ove
r time are discussed.