|The TCALIS Procedure|
You can use the RENAMEPARM statement to rename parameters or to change the types of parameters of a reference model so that new parameters are transferred to the new model in question. The RENAMEPARM statement is a subsidiary model specification statement that should be used together with the REFMODEL statement. The syntax of the RENAMEPARM statement is similar to that of the STD statement—except that in the RENAMEPARM statement, you put parameter names on the left-hand side of equal signs, whereas you put variable names on the left-hand side in the STD statement. You can use no more than one RENAMEPARM statement within the scope of each REFMODEL statement.
In the REFMODEL statement, you transfer all the model specification information from a base model to the new model being specified. The RENAMEPARM statement enables you to modify the parameter names or types in the base model before transferring them to the new model. For example, in the following example, you define model 2, which is a new model, by referring it to model 1, the base model, in the REFMODEL statement.
model 1; lineqs V1 = F1 + E1, V2 = b2 F1 + E2, V3 = b3 F1 + E3, V4 = b4 F1 + E4; std F1 = vF1, E1-E4 = ve1-ve4; model 2; refmodel 1; renameparm ve1-ve4=new1-new4, b2=newb2(.2), b4=.3;
Basically, the LINEQS model specification in model 1 is transferred to model 2. In addition, you redefine some parameters in the base model by using the RENAMEPARM statement. This example illustrates two kinds of modifications that the RENAMEPARM statement can do:
creating new parameters in the new model
The error variances for E1–E4 in model 2 are different from those defined in model 1 because new parameters new1–new4 are now used. Parameter b2 is renamed as newb2 with a starting value at 0.2 in model 2. So the two models have distinct path coefficients for the F1-to-V2 path.
changing free parameters into fixed constants
By using the specification b4=.3 in the RENAMEPARM statement, b4 is no longer a free parameter in model 2. The path coefficient for the F1-to-V4 path in model 2 is now fixed at 0.3.
The RENAMEPARM statement is handy when you have just few parameters to change in the reference model defined by the REFMODEL statement. However, when there are a lot of parameters to modify, the RENAMEPARM statement might not be very efficient. For example, to make all parameters unique to the current model, you might consider using the ALLNEWPARMS, PARM_PREFIX, or PARM_SUFFIX option in the REFMODEL statement.
Note: This procedure is experimental.