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  • Please check my interaction test code after multiple imputation.

    Dear statalist,

    What I want to do is test the interaction with CKD status(factor) and IGF10(continuous) with a multiple imputed dataset.
    In complete case analysis, I do that like this:

    stset time_mortal, f(ev_mortal==1) scale(365.25) id(n_eid)
    stcox IGF10 $C c.IGF10##i.CKD
    testparm c.IGF10##i.CKD


    In the multiple imputation dataset, there is no exact 'testparm' for the interaction,
    so I did this code. :

    mi stset time_mortal, f(ev_mortal==1) scale(365.25) id(n_eid)

    mi xeq: stcox IGF10 $C c.IGF10##i.CKD
    mi xeq: testparm c.IGF10##i.CKD

    After that, Prob>chi2 were 0.000 for every imputed dataset, like this.

    (previous this code, there were 5 sets of stcox results from m=0 to m=5.)

    . mi xeq: testparm c.IGF10##i.CKD

    m=0 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000

    m=1 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000

    m=2 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000

    m=3 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000

    m=4 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000

    m=5 data:
    -> testparm c.IGF10##i.CKD

    ( 1) IGF10 = 0
    ( 2) 1.CKD = 0
    ( 3) 1.CKD#c.IGF10 = 0

    chi2( 3) = 351.01
    Prob > chi2 = 0.0000



    I wonder... can I translate it as P for interaction <0.001?
    Could anyone know how to estimate the 'real' P for interaction using Rubin's rule?
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