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From |
"Florian Christian Esser" <florian.esser@tu-dortmund.de> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: CR and AVE for factor analysis with 2 factors |

Date |
Tue, 29 Oct 2013 10:07:21 +0100 |

Here we go (I included the uniqueness and the loadings as well). Communalities are on the bottom: _____________________________________________________________ . matrix list e(Psi) e(Psi)[1,6] zwmdiff_1 zwpdiff_1 zwpdiff_2 zwcost_1 zwcost_2 zwcost_3 Uniqueness .14721836 .16061008 .12541414 .01425274 .01366305 .02630422 . matrix list e(L) e(L)[6,3] Factor1 Factor2 Factor3 zwmdiff_1 .81629684 .233233 .36337787 zwpdiff_1 .82275816 .39938175 -.05434294 zwpdiff_2 .8671496 .34761446 .04244559 zwcost_1 -.52875169 .83417333 .10160593 zwcost_2 -.51348298 .84223386 .11538764 zwcost_3 -.18959666 -.28021389 .9269461 . matrix psi = e(Psi)' . matrix communalities = J(rowsof(psi),1,1) . matrix communalities = communalities - psi . matrix colnames communalities = communalities . matrix list communalities communalities[6,1] communalit~s zwmdiff_1 .85278164 zwpdiff_1 .83938992 zwpdiff_2 .87458586 zwcost_1 .98574726 zwcost_2 .98633695 zwcost_3 .97369578 _____________________________________________________ > What is implied by your log is that > > replace sum_factors = sum_factors + sqrt(communalities[3,1]) > > has the effect of replacing -sum_factors- with missing. So, please > show us that -communalities- matrix, > namely the result of your line > > matrix list communalities > > (I see on closer examination that the -communalities- matrix is not > the communalaties as first reported, but modified.) > > No idea, sorry, about your general factor analysis question. I'm > firmly a PCA person. > Nick > njcoxstata@gmail.com > > > On 29 October 2013 07:14, Florian Christian Esser > <florian.esser@tu-dortmund.de> wrote: >> Hi Nick, thanks a lot for your advice. >> Unfortunately, all my communalities are positive. >> Does anyone have any ideas, what else could cause the issue? >> >> Is the general approach correct, to calculate CR and AVE for both >> factors >> at the same time, or would I have to do it individually. I.e. I do the >> factor analysis, identify, that the indicators load on two factors and >> then calculate CR and AVE for each factor individually? >> >>> Your missing value is presumably the result of taking the square root >>> of a negative number. Is at least one of your communalities reported >>> as negative? >>> >>> That aside you have segments like >>> >>> gen nvar = e(df_m) >>> gen sum_factors=0 >>> local i=1 >>> while `i' <= nvar { >>> replace sum_factors = sum_factors + sqrt(communalities[`i',1]) >>> local i=`i'+1 >>> } >>> >>> You can simplify this. First, to hold constants, use locals or >>> scalars, not variables. Second, use -forval- to loop here: >>> >>> local nvar = e(df_m) >>> local sum_factors = 0 >>> forval i = 1/`nvar' { >>> local sum_factors = `sum_factors' + sqrt(communalities[`i',1] >>> } >>> >>> Third, use Mata instead. Here is a self-contained example: >>> >>> . matrix foo = (1,2,3,4) >>> >>> . mata : st_numscalar("sum_factors", sum(sqrt(st_matrix("foo")))) >>> >>> . scalar li >>> sum_factors = 6.1462644 >>> >>> However, none of these tricks can get round what appears to be your >>> problem. >>> >>> >>> Nick >>> njcoxstata@gmail.com >>> >>> >>> On 28 October 2013 14:11, Florian Christian Esser >>> <florian.esser@tu-dortmund.de> wrote: >>>> Hi everyone, >>>> >>>> I am trying to do factor analysis in order to measure two strategy >>>> constructs. I have 6 indicators that load on these two constructs. Now >>>> I >>>> want to calculate composite reliability (CR) and average variance >>>> extracted(AVE). >>>> I use the following code (here for CR): >>>> ___________________________________________________________________ >>>> factor zwmdiff_1 zwpdiff_1 zwpdiff_2 zwcost_1 zwcost_2 zwcost_3, pcf >>>> matrix list e(Psi) >>>> matrix list e(L) >>>> matrix psi = e(Psi)' >>>> matrix communalities = J(rowsof(psi),1,1) >>>> matrix communalities = communalities - psi >>>> matrix colnames communalities = communalities >>>> matrix list communalities >>>> gen nvar = e(df_m) >>>> gen sum_factors=0 >>>> local i=1 >>>> while `i' <= nvar { >>>> replace sum_factors = sum_factors + sqrt(communalities[`i',1]) >>>> local i=`i'+1 >>>> } >>>> generate sum_psi=0 >>>> local i=1 >>>> while `i' <= nvar { >>>> replace sum_psi = sum_psi + psi[`i',1] >>>> local i=`i'+1 >>>> } >>>> gen cr=(sum_factors*sum_factors)/((sum_factors*sum_factors)+sum_psi) >>>> drop nvar >>>> drop sum_factors >>>> drop sum_psi >>>> list cr in 1 >>>> _________________________________________________________________ >>>> >>>> The problem is that once the local macro starts running it tells me: >>>> _____________________________ >>>> [...] >>>> (534 real changes made) >>>> (534 real changes made) >>>> (534 real changes made, 534 to missing) >>>> (0 real changes made) >>>> (0 real changes made) >>>> (0 real changes made) >>>> [...] >>>> ___________________________ >>>> >>>> and accordingly there is an empty result for CR. >>>> If I add "factors(1)" in the command line above, I get a result, but I >>>> since I have two factors, I think it is not correct to do this. >>>> >>>> Does anyone know what to do here? >>>> >>>> Thanks a lot in advance. >>>> >>>> * >>>> * For searches and help try: >>>> * http://www.stata.com/help.cgi?search >>>> * http://www.stata.com/support/faqs/resources/statalist-faq/ >>>> * http://www.ats.ucla.edu/stat/stata/ >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/faqs/resources/statalist-faq/ >>> * http://www.ats.ucla.edu/stat/stata/ >>> >> >> >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: CR and AVE for factor analysis with 2 factors***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: CR and AVE for factor analysis with 2 factors***From:*"Florian Christian Esser" <florian.esser@tu-dortmund.de>

**Re: st: CR and AVE for factor analysis with 2 factors***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: CR and AVE for factor analysis with 2 factors***From:*"Florian Christian Esser" <florian.esser@tu-dortmund.de>

**Re: st: CR and AVE for factor analysis with 2 factors***From:*Nick Cox <njcoxstata@gmail.com>

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