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My question involves a MIMIC model where I intend to compare a baseline LGM to an LGM nested within it (wherein intercept and slope paths are freed) using the traditional Chi-square difference test. My (abbreviated) syntax is included below: BASELINE MODEL: GROUPING IS PRCATO15_2cat (1 = secure 2 = insecure); MODEL: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I S on L08X5MEAN_R; STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); OUTPUT: SAMPSTAT; STANDARDIZED; NESTED MODEL: GROUPING IS PRCATO15_2cat (1 = secure 2 = insecure); MODEL: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I S on L08X5MEAN_R; STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL secure: I S on L08X5MEAN_R; OUTPUT: SAMPSTAT; STANDARDIZED; When I run this syntax, the degrees of freedom between the baseline and nested models are identical. How is this possible if I'm specifying the freeing of I S on L08X5MEAN_R; for the secure group? I appreciate any help you can provide. |
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There is no difference between the two models. The ON statement you mention in the group-specific MODEL command is not constrained to be equal as the default. |
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To make the statement "I S on L08X5MEAN_R" equal between groups the default in the baseline model, would this work: BASELINE MODEL: GROUPING IS PRCATO15_2cat (1 = secure 2 = insecure); MODEL: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I S on L08X5MEAN_R; STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL secure: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1(p1); I S on L08X5MEAN_R(p2); STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL insecure: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1(p3); I S on L08X5MEAN_R(p4); STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL CONSTRAINT: 0 = p1 - p3 0 = p2 - p4 OUTPUT: SAMPSTAT; STANDARDIZED; Thanks again for your help! |
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You should place the equality in the general MODEL command: MODEL: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I on L08X5MEAN_R (10); S on L08X5MEAN_R (11); |
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So, just to be clear, the syntax would read: BASELINE MODEL: GROUPING IS PRCATO15_2cat (1 = secure 2 = insecure); MODEL: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I on L08X5MEAN_R (10); s on L08X5MEAN_R (11); STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL secure: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I on L08X5MEAN_R (10); s on L08X5MEAN_R (11); STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); MODEL insecure: I S | STANXX1F@0 STANXXG3@.25 STANXXG5@.5 STANXXG6@.6 STANXXX5@1; I on L08X5MEAN_R (10); s on L08X5MEAN_R (11); STANXX1F STANXXG3 STANXXG5 STANXXG6 STANXXX5(1); OUTPUT: SAMPSTAT; STANDARDIZED; Thanks again! |
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You don't need the group-specific MODEL commands. They are redundant. There is a section in Chapter 14 of the user's guide that discusses multiple group analysis. |
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