The second approach is the correct approach. When you run an interaction (moderation) model, the individual terms reflect the value of that term when all other terms are equal to 0. In this
case that means centEO is the coefficient when centAFFIL_PHIL is equal to zero and INTER_centEOxcentAFFIL_PHIL (which would be the case when centAFFIL_PHIL is equal to zero, since the product of anything and zero is zero. Remember that the interaction term
(INTER_centEOxcentAFFIL_PHIL) is the modification to the slope values of the individual terms. With continuous terms this all becomes somewhat ambiguous and so the strong suggestion I give to everyone is to plot the interactions.
Matthew J Poes
Research Data Specialist
Center for Prevention Research and Development
University of Illinois
510 Devonshire Dr.
Champaign, IL 61820
Phone: 217-265-4576
email: [hidden email]
From: SPSSX(r) Discussion [mailto:[hidden email]]
On Behalf Of Onishi, Tamaki
Sent: Tuesday, October 23, 2012 12:36 AM
To: [hidden email]
Subject: Moderated regression
Hello,
I am trying to run moderated regression, but am not confident if I am doing correct and did 2 different ways. My questions are (1) Could anybody let me know which one is correct or if neither is
correct what I should do? And (2) which result of "Sig." should I report as related to the coefficients?
I am attaching one example. Here, a research question is "how EO affects the relationship between DV (VPTOOL2) and affiliation with philanthropic associations."
Also, EO below is labeled as "centEO"[as this was centered] or "INTER_centEO" as part of a moderating (interaction) term, whereas affiliation with philanthropic associations, as "centAFFIL_PHIL".
Thanks much for your help!
|
Example 1) |
|||||||||||||
|
Model |
Unstandardized Coefficients |
Standardized Coefficients |
t |
Sig. |
95.0% Confidence Interval for B |
Correlations |
Collinearity Statistics |
||||||
|
B |
Std. Error |
Beta |
Lower Bound |
Upper Bound |
Zero-order |
Partial |
Part |
Tolerance |
VIF |
||||
|
1 |
(Constant) |
9.342 |
.393 |
|
23.762 |
.000 |
8.560 |
10.123 |
|
|
|
|
|
|
centAFFIL_PHIL |
-1.412 |
.259 |
-.508 |
-5.443 |
.000 |
-1.928 |
-.896 |
-.508 |
-.508 |
-.508 |
1.000 |
1.000 |
|
|
2 |
(Constant) |
9.344 |
.396 |
|
23.597 |
.000 |
8.557 |
10.132 |
|
|
|
|
|
|
centAFFIL_PHIL |
-1.410 |
.261 |
-.508 |
-5.401 |
.000 |
-1.930 |
-.891 |
-.508 |
-.508 |
-.507 |
.998 |
1.002 |
|
|
INTER_centEOxcentAFFIL_PHIL |
.042 |
.311 |
.013 |
.134 |
.894 |
-.577 |
.661 |
.034 |
.015 |
.013 |
.998 |
1.002 |
|
|
a. Dependent Variable: VPTOOL2 |
|||||||||||||
|
Example 2) |
|||||||||||||
|
Model |
Unstandardized Coefficients |
Standardized Coefficients |
t |
Sig. |
95.0% Confidence Interval for B |
Correlations |
Collinearity Statistics |
||||||
|
B |
Std. Error |
Beta |
Lower Bound |
Upper Bound |
Zero-order |
Partial |
Part |
Tolerance |
VIF |
||||
|
1 |
(Constant) |
9.342 |
.395 |
|
23.622 |
.000 |
8.555 |
10.128 |
|
|
|
|
|
|
centEO |
-.018 |
.457 |
-.004 |
-.040 |
.969 |
-.927 |
.891 |
.023 |
-.004 |
-.004 |
.997 |
1.003 |
|
|
centAFFIL_PHIL |
-1.412 |
.261 |
-.509 |
-5.405 |
.000 |
-1.932 |
-.893 |
-.508 |
-.508 |
-.508 |
.997 |
1.003 |
|
|
2 |
(Constant) |
9.345 |
.398 |
|
23.456 |
.000 |
8.552 |
10.137 |
|
|
|
|
|
|
centEO |
-.023 |
.461 |
-.005 |
-.050 |
.960 |
-.941 |
.894 |
.023 |
-.006 |
-.005 |
.990 |
1.010 |
|
|
centAFFIL_PHIL |
-1.411 |
.263 |
-.508 |
-5.365 |
.000 |
-1.934 |
-.888 |
-.508 |
-.507 |
-.507 |
.996 |
1.004 |
|
|
INTER_centEOxcentAFFIL_PHIL |
.043 |
.314 |
.013 |
.137 |
.891 |
-.582 |
.668 |
.034 |
.015 |
.013 |
.991 |
1.009 |
|
|
a. Dependent Variable: VPTOOL2 |
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