Moderation (05/29/2006) Y-hat = b0 + b1X + b2Z + b3XZ, where Y, X, Z are continuous.e.g. %TestModeration(data=mydata,y=DV,x=IV,mod=moderator); %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,plot=yes); %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,plot=yes,plotline=3); %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,TestSimpleSlope=yes); %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,SimpleOutput=no); Want to retain the standard deviation of X and Z? Add SD_1=no, e.g., %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,SD_1=no); Want to add means of X and Z to the plot? Add AddMeanInPlot=yes, e.g., %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,AddMeanInPlot=yes); Want to plot a 3D graph (Behrens & Yu, 1994)? Add plot3D=yes, e.g., %TestModeration(data=mydata,y=DV,x=IV,mod=moderator,plot=yes,plot3D=yes); Want to have a short output? Add the parameter verbose=no.
= (b0 + b2Z) + (b1 + b3Z)X e.g. %SimpleSlope(data=mydata,y=DV,x=IV,z=conditional variable,zcv=1); where zcv means conditional value for the conditional variable
All parameters are the same as in %TestModeration, except mod1=, mod2=. e.g. %Test3wayMod(data=mydata,y=DV,x=IV,mod1=Z,mod2=W); %Test3wayMod(data=mydata,y=DV,x=IV,mod1=Z,mod2=W,plot=yes); Want to have a short output? Add the parameter verbose=no. Want to have separate graphs for W=low and high (Aiken & West, 1991), change the parameter plotcombine=no. Want to test for simple slope differences (Dawson & Richter, in press)? Add the paramter TestSimpleSlopeDiff=yes.
= (b0 + b3W) + (b1 + b5W)X + (b2 + b6W)Z + (b4 + b7W)XZ e.g. %ConditionalMod(data=mydata,y=DV,x=IV,z=moderator,w=conditional variable,wcv=1); where wcv means conditional value for the conditional variable Y-hat = b0 + b1X + b2X² + b3Z + b4XZ + b5X²Z All parameters are similar as in %TestModeration. e.g. %TestModeration2(data=mydata,y=DV,x=IV,mod=moderator,plot=yes); Y and X are continuous; moderator is nominal (Cohen, Cohen, West, & Aiken, 2003) The nominal variable has p levels and is represented by (p-1) dummy variables. When p=3, Y-hat = b0 + b1X + b2D1 + b3D2 + b4XD1 + b5XD2 e.g. %TestNominalMod(data=mydata,y=DV,x=IV,mod=moderator); Polyserial correlation (06/17/2006)
References
* Behrens, J. T., & Yu, C. H. (1994, June). The visualization of multi-way interactions and high-order terms in multiple regression. Paper presented at the Annual Meeting of the Psychometric Society, Urbana-Champaign, IL. * Cohen, J., Cohen, P., West, S. G., & Aiken, L. S. (2003). Applied multiple regression/correlation analysis for the behavioral sciences (3rd ed.). Mahwah, NJ: Lawrence Erlbaum. * Dawson, J. F., & Richter, A. W. (2006). Probing three-way interactions in moderated multiple regression: Development and application of a slope difference test. Journal of Applied Psychology.
* Joreskog, K.G. (1986). Estimation of the polyserial correlation from summary statistics. Research Report 86-2. Uppsala: University of Uppsala, Department of Statistics. * Olsson, U., Drasgow, F., & Dorans, N. J. (1982). The polyserial correlation coefficient. Psychometrika, 47(3), 337-347. |