Hi, I am puzzeled with a differing result of princomp in R and FACTOR in SPSS. Regarding the amount of explained Variance, the two results are the same. However, the loadings differ substantially, in the unrotated as well as in the rotated form. In both cases correlation matrices are analyzed. The sums of the squared components is one in both programs. Maybe there is an obvious reason, but I somehow fail to see it.
Best Regards Andreas This is the output generated by R: pc<-princomp(dat[,-c(1,2)],cor=T) > pc$loadings[,1:2] Comp.1 Comp.2 DS140_01 -0.2040579 -0.3837623 DS140_02 0.2351527 -0.3241166 DS140_03 -0.1391408 -0.3864510 DS140_04 0.2784596 -0.2512202 DS140_05 0.2823365 -0.2779157 DS140_06 0.2928942 0.1218132 DS140_07 0.2601528 -0.1162116 DS140_08 0.2737338 0.2811998 DS140_09 0.3012719 -0.1714994 DS140_10 0.2653410 0.3159160 DS140_11 0.2590944 0.2347922 DS140_12 0.2837112 -0.2653533 DS140_13 0.3246268 -0.2187217 DS140_14 0.2896170 0.2190227 > varimax(pc$loadings[,1:2]) $loadings Loadings: Comp.1 Comp.2 DS140_01 -0.424 DS140_02 0.390 DS140_03 0.146 -0.384 DS140_04 0.375 DS140_05 0.395 DS140_06 0.143 0.283 DS140_07 0.273 DS140_08 0.392 DS140_09 0.340 DS140_10 0.413 DS140_11 0.347 DS140_12 0.388 DS140_13 0.389 DS140_14 0.355 Comp.1 Comp.2 SS loadings 1.000 1.000 Proportion Var 0.071 0.071 Cumulative Var 0.071 0.143 $rotmat [,1] [,2] [1,] 0.7585207 0.6516489 [2,] -0.6516489 0.7585207 This is the output generated by SPSS Call: FACTOR /VARIABLES ds140_01 ds140_02 ds140_03 ds140_04 ds140_05 ds140_06 ds140_07 ds140_08 ds140_09 ds140_10 ds140_11 ds140_12 ds140_13 ds140_14 /MISSING LISTWISE /ANALYSIS ds140_01 ds140_02 ds140_03 ds140_04 ds140_05 ds140_06 ds140_07 ds140_08 ds140_09 ds140_10 ds140_11 ds140_12 ds140_13 ds140_14 /PRINT INITIAL EXTRACTION ROTATION /FORMAT BLANK(.10) /CRITERIA MINEIGEN(1) ITERATE(25) /EXTRACTION PC /CRITERIA ITERATE(25) /ROTATION VARIMAX /METHOD=CORRELATION . unrotaded loadings DS140_01 -0,472589983 0,56095286 DS140_02 0,54460413 0,47376757 DS140_03 -0,322244458 0,564883041 DS140_04 0,644901386 0,367213521 DS140_05 0,653880049 0,406234844 DS140_06 0,678331281 -0,178056681 DS140_07 0,602503396 0,169868767 DS140_08 0,633956607 -0,411035327 DS140_09 0,697733664 0,250684012 DS140_10 0,614519123 -0,461780638 DS140_11 0,60005226 -0,3432004 DS140_12 0,657063717 0,387872152 DS140_13 0,751822595 0,319709742 DS140_14 0,670741388 -0,320149821 rotated lodings DS140_01 -0,733417555 DS140_02 0,721512351 DS140_03 0,108433988 -0,641230389 DS140_04 0,731634009 0,124319125 DS140_05 0,763297939 DS140_06 0,412130295 0,567438215 DS140_07 0,573827679 0,250175009 DS140_08 0,230223944 0,719616533 DS140_09 0,698707567 0,2479566 DS140_10 0,183040757 0,746572965 DS140_11 0,246954311 0,645649128 DS140_12 0,754130666 0,11603651 DS140_13 0,78428374 0,228802423 DS140_14 0,316255625 0,672586274 rotation matrix 1 2 1 0,773826782 0,633397277 2 0,633397277 -0,773826782 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html