# Thread: How do I compare the strength of relationships across three groups (in SPSS)?

1. ## How do I compare the strength of relationships across three groups (in SPSS)?

Hi everyone,

I have data from three countries (US, Spain, and Germany), and ran a separate mediation analysis for each one using four variables: one IV (TFL_HSA), two mediators (RA and RO_RC), and one DV (Anxiety). My results showed very different regression coefficients between each group, which leads me to believe that there are differences in the strengths of each relationship between each group.

My question is this: how can I tell which groups specifically are scoring higher/lower than the others? I created dummy codes for country (c_US_ESP and c_US_GER) and did the following (SPSS syntax below), which tells me that there are significant differences in regression weights between groups for each relationship, but it doesn't tell me, for example, whether the relationship between TFL_HSA and RA is significantly stronger in the US sample than in both the German or Spanish, or if it's significantly stronger than just the Spanish, etc. Is there some sort of post-hoc analysis I can do to figure this out?

Another idea I had was to do three sets of analyses using Fisher's r-to-z (comparing regression weights for US and Spain, then US and Germany, then Spain and Germany). I know that this will drive up my Type I error, but I'm not sure how else to do what I want to do.

compute country1TFL = c_US_ESP*TFL_HSA.
compute country2TFL = c_US_GER*TFL_HSA.
compute country1RA = c_US_ESP*RA.
compute country2RA = c_US_GER*RA.
compute country1RO_RC = c_US_ESP*RO_RC.
compute country2RO_RC = c_US_GER*RO_RC.
execute.

regression
/dep RA
/method = enter TFL_HSA
/method = test(c_US_ESP c_US_GER)
/method = test(country1TFL country2TFL).
execute.

regression
/dep RO_RC
/method = enter TFL_HSA
/method = test( c_US_ESP c_US_GER)
/method = test(country1TFL country2TFL).
execute.

regression
/dep Anxiety
/method = enter TFL_HSA
/method = test(c_US_ESP c_US_GER)
/method = test(country1TFL country2TFL)
execute.

regression
/dep Anxiety
/method = enter RA
/method = test(c_US_ESP c_US_GER)
/method = test(country1RA country2RA)
execute.

regression
/dep Anxiety
/method = enter RO_RC
/method = test(c_US_ESP c_US_GER)
/method = test(country1RO_RC country2RO_RC)
execute.

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