On Wed, 30 Apr 2008 04:04:13 -0400, Ingo.Frommann@ukb.uni-bonn.de <ingo.frommann@UKB.UNI-BONN.DE> wrote:

>Dear All, > >I have a question about the use of ANCOVA. In a repeated measure >design with three levels, (neuropsychlogical domains: memory, >executive, attention) on the within subject factor and three levels on >the between subject factor (Controls, Group2, Group3), i want to >correct for psychopathological symptoms which were present only in >Group2 and Group3, but not in the control group. > >Thus, I added for all controls zero on the symptom varibale and tried >to use the following syntax. > >GLM > np_memo np_exec np_atten BY group WITH symptoms > /WSFACTOR = domain 3 Polynomial > /METHOD = SSTYPE(3) > /EMMEANS = TABLES(group) WITH(symptoms=MEAN) COMPARE ADJ(BONFERRONI) > /EMMEANS = TABLES(group*domain) WITH(symptoms=MEAN) >COMPARE(eproject) ADJ(BONFERRONI) > /PRINT = DESCRIPTIVE ETASQ PARAMETER HOMOGENEITY GEF > /CRITERIA = ALPHA(.05) > /WSDESIGN = domain > /DESIGN = eproject*cor_pans_pos eproject. > >I have the following questions: >1. Did produce this syntax covariates which were estimated separate >for each group and each neuropsychological domain? >2. Were main effects and interactions in the output based on adjusted >means corrected for theinfluence of the covariate? >3. Is it possible with the EMMEANS subcommand to compare the adjusted >means of the groups. Only group2 were compared against group3 in my >outputs? Is it possible to use a more hirarchical procedure, where >first the effects of the covariates were eleminated and then the >groups were compared against each other? How can I do this with >SPSS? >4. Is it possible to save the adjusted values for each case in the >data sheet? > >Thank you very much for your reply, >best regards > >Ingo > >===================== >To manage your subscription to SPSSX-L, send a message to >LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the >command. To leave the list, send the command >SIGNOFF SPSSX-L >For a list of commands to manage subscriptions, send the command >INFO REFCARD

Dear all,

Sorry, the submitted command syntax needs some correction:

GLM np_memo np_exec np_atten BY group WITH symptoms /WSFACTOR = domain 3 Polynomial /METHOD = SSTYPE(3) /EMMEANS = TABLES(group) WITH(symptoms=MEAN) COMPARE ADJ(BONFERRONI) /EMMEANS = TABLES(group*domain)WITH(symptoms=MEAN)COMPARE(group) ADJ(BONFERRONI) /PRINT = DESCRIPTIVE ETASQ PARAMETER HOMOGENEITY GEF /CRITERIA = ALPHA(.05) /WSDESIGN = domain /DESIGN = group*symptoms group.

I did not find a simple solution for my problem in SPSS, so I calculated simple linear regression analysis for all dependent variables with variable "symptoms" as predictor within each clinical group (group1 and group2). I get a linear equitation for each dependent variable and each group: Y = B*X + c + e, where Y is the dependent variable, x the symptoms, B the estimated coefficient,c the constant, and e the residual. Then I adjusted all dependent variables by subtracting the estimated effect from the empirical data by calculating: Ya = Y - B*X , where Ya is the adjusted domain score. For the control group I copy the original data. Finally with the adjusted variables I conduct a simple MANOVA:

np_memo_a np_exec_a np_atten_a BY group /WSFACTOR = domain 3 Polynomial /METHOD = SSTYPE(3) /EMMEANS = TABLES(group) COMPARE ADJ(BONFERRONI) /EMMEANS = TABLES(group*domain)COMPARE(group) ADJ(BONFERRONI) /PRINT = DESCRIPTIVE ETASQ PARAMETER HOMOGENEITY GEF /CRITERIA = ALPHA(.05) /WSDESIGN = domain /DESIGN = group.

I do not know, whether this procedure was correct? Any advice appreciated!

Thanks, Ingo

===================== To manage your subscription to SPSSX-L, send a message to LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD