HI AFNI Experts,

We were trying to create GLT codes for interactions of continuous variables, and we keep getting the generic 3dLME error (I’m assuming we’re specifying our GLT for continuous variable interactions incorrectly).

For example, the following code without the interactions works (script 1):

3dLME

-prefix $out_file

-jobs 4

-model “con_linear*age_w1*lag_years”

-qVars “con_linear,age_w1,lag_years”

-ranEff “~1+con_linear”

-SS_type 3

-mask $mask_file

-num_glt 3

-gltLabel 1 ‘linear’ -gltCode 1 ‘con_linear :’

-gltLabel 2 ‘age’ -gltCode 2 ‘age_w1 :’

-gltLabel 3 ‘lag’ -gltCode 3 ‘lag_years :’

-dataTable @${data_table}

However, the following code with interactions does not work (script 2):

3dLME

-prefix $out_file

-jobs 4

-model “con_linear*age_w1*lag_years”

-qVars “con_linear,age_w1,lag_years”

-ranEff “~1+con_linear”

-SS_type 3

-mask $mask_file

-num_glt 7

-gltLabel 1 ‘linear’ -gltCode 1 ‘con_linear :’

-gltLabel 2 ‘age’ -gltCode 2 ‘age_w1 :’

-gltLabel 3 ‘lag’ -gltCode 3 ‘lag_years :’

-gltLabel 4 ‘linear_x_age’ -gltCode 4 ‘con_linear : age_w1 :’

-gltLabel 5 ‘lag_x_age’ -gltCode 5 ‘lag_years : age_w1 :’

-gltLabel 6 ‘linear_x_lag’ -gltCode 6 ‘con_linear : lag_years :’

-gltLabel 7 ‘linear_x_age_x_lag’ -gltCode 7 ‘con_linear : age_w1 : lag_years :’

-dataTable @${data_table}

- What is the correct way to specify GLTs for the interactions of continuous variables?
- Is there a way to specify GLTs after 3dLME has already been run?
- The results from script 1 return what I think are estimates/regression coefficients and a z-test (rather than a t-test), is this correct?

Thank you!,

Ekarin