I ran an EFA and Bifactor and got identical model fit for a two-factor solution (2 factors in EFA, 1 General and 1 Residual factor in Bi-EFA).
Is it possible to have identical fit from two different analyses? The values are perfectly identical. Interestingly, in both cases, the 2-factor (identical) fit is the best.
Your input is much appreciated!
My syntax for EFA: TITLE:EFA 1-4 factors DATA: File is XXX.csv; VARIABLE: NAMES ARE Itm1-Itm18; USEVARIABLES ARE Itm2-Itm15 Itm18; ANALYSIS: TYPE = EFA 1 4; OUTPUT: MODINDICES; plot: type = plot2;
My syntax for Bi-EFA TITLE: Bi-EFA Using ESEM DATA: File is XXX.csv; VARIABLE: NAMES ARE Itm1-Itm18; USEVARIABLES ARE Itm2-Itm15 Itm18; ANALYSIS: ROTATION = BI-GEOMIN; MODEL: fg f1 BY Itm2-Itm15 Itm18 (*1);
Bi-factor EFA with m-1 specific factors is equivalent to EFA with m factors, that is, the two types of models have the same fit to data. The two models are reparameterizations of each other, so that the bi-factor EFA represents a special type of rotation.