# Statistics Questions

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• #3099

Use this to post statistics questions

#3182
Harry Lim
Member

Hi Andy,

I carried out a Condition (4 levels) x Distance (2 levels) repeated measures ANOVA, with bonferroni adjustment. There was a significant main effect for condition, but pairwise comparisons on SPSS did not show any significant effects between any conditions. I wanted to find out if the right thing to do is to carry out multiple t-tests, and then use a corrected p value to test for significance?

#3181

In programmes like SPSS/R you can get it to do the correction for you. The trouble with post hogs is that they can be relatively insensitive, which might be why you’re missing the difference that is driving the main effect. In general you’re probably better off just looking at the confidence intervals around the group means, computing some effect sizes for differences between conditions, and using those for interpretation. Also, if your condition * distance interaction is significant then ignore the main effects altogether.

andy

#3180
Angel Carrasco
Participant

Maybe I run the risk of being annoying but I have realized I posted this in the wrong place so I’ll copypaste plus add some clarification:

Dear Andy and everybody,

A.C.

Update: The problem is, of course, not simply to calculate and interpret an interaction effect in a repeated measures ANOVA. The interaction that interests me is one between a continuous variable and a repeated measures categorical effect. So everybody’s saying that I should use RM and not doing median splits, but I can only find instructions for factorial between-subjects designs. Thanks again for reading this.

#3179

Hey There,

I am a graduate student, currently working on my Master’s
thesis. I am attempting to analyze differential carryover effects for a
within-subjects design. I have three conditions, counterbalanced of course, and
I would like to see how early exposure to one or two conditions affects the
other(s). If anyone knows of anything to point me in the correct direction on
how to set up and analyze this in SPSS, or any other statistical programs, I
would greatly appreciate it. Also, I have been trying to find research that
have already analyzed a similar design but have not had any luck there. So if
this approach rings any memory bells, then please pass along that info.

Thank you very much for your time.

-Mike

#3178

so sorry – i just sent an e-mail with the below questions to all members of this group. Clearly a first time user.

Two questions regarding specifics of Multiple Imputation in SPSS

A: The default setting for m is 5. Does the program make m imputations required for your data set (sort of like iterations) or does it create m data sets that are specified. I have generally read that m is usually between 3 and 10. If we set m to ten, will it stop when it needs to (e.g., maybe 8) or does it compute 10 imputations?

B: Currently we have 5 imputed data sets. What do we use as our “new” data set? Do we aggregate these sets somehow? What is the next step so we can get back to hypothesis testing?  🙂

#3177
Jeremy Miles
Participant

I think that SPSS makes m datasets (I’m not sure, I haven’t used SPSS for this).  You then analyze these m datasets, and combine the results, there should be a way of doing this in SPSS.

SPSS makes as many datasets as you tell it to.  Although 3 or 5 is often used as the standard, you sometimes need many more.  I’ve needed 50 on one occasion, and I’ve heard of people needing hundreds.  When you analyze the data, you’ll get a t-statistic, this tells you if you had enough imputations.

I suggest the book Missing Data, by Paul Allison.

#3176

thank you for the response. I will check out the book, and keep increasing m until the t-statistic comes out significant. I would like specific direction about combining the results.

#3175

Anyone able to give direction about combining the results from multiple imputations of missing data from SPSS?

#3174

Hi,

I’m confusing the hell out of myself so could someone please clarify if a mixed factorial ANOVA is the same as a repeated measures ANOVA.

The design I’ve currently been forced to look at has 120 participants split into 4 groups. It is a 2 (gender) x 2 (treatment condition) x 3 (time) repeated measure design, where there are: 2 between subjects factors (gender and treatment) and 1 within subject factor (time). Dependent variable is reported alcohol consumption.

Apparently a mixed ANOVA is a mixture of between group and repeated measures variables and should have at least one d.v (alcohol consumption) and at least 2 i.v’s with at least one between groups. (course and gender) and one within groups (time). This allows you to test two between groups (course and sex) and one repeated measures (time) though it’s a more complex design. As my question falls into this design I was just wondering if some bright spark decided to use different names for the same test or if they are completely different. Thanks 🙂

#3173
David Kronemyer
Participant

Good morning Dr. Field, I started off with 32 predictor variables and successfully completed factor analysis to reduce them to four constructs.  No real interest in assigning factor loadings to each one of the predictors.  Rather I want to use the four factor scores as new predictor variables in a regression analysis.  At p. 636 text states this can be done but doesn’t set forth an operational procedure.  What SPSS output does one use?  Are they coefficients, do you have to multiply them by something (what?), or add them together?  Several of the original predictor variables used different measurement scales.  At p. 633 the text says that as a result, different factor scores can’t be compared.  Do you have to normalize them in order to use them as new predictors?  Or is this obviated by using the “Anderson-Rubin method” described at p. 635?  I could use some advice from Jane Superbrain, thanks in advance.  DAVID

#3172
Issac
Member

Good Day Professor Field.

I have a couple of questions regarding factor analysis in non-standard scenarios – I think.

The background is I have 10 questions on a 360-degree evaluation scale that is being used routinely to monitor performance. So multiple evaluators assess multiple evaluatees over time. Eg. Evaluator A assessed 5 persons (evaluateees 1,2,3,4,5) multiple times over the year. Evaluatee 1 is assessed by multiple evaluators (e.g., evaluators A, B, C, D, E).

What are the steps that I need to do to prepare my data before for a factor analysis? Should I slice my dataset into a few parts (according to evaluatees / evaluators)? Is there a relevant reference that I can read more about this?

Thank you!

#3171
RH
Member

Hi

Technically a repeated measures factorial ANOVA is where all your IVs are repeated measures (i.e. there are no independent groups) . The Mixed ANOVAl is where you have at least one repeated measures IV and at least one between-subjects IV.

The confusion comes because in SPSS you have to use the repeated-measures option under the GLM to do the mixed ANOVA.

In short, to analyse your experiment do Analyse>GLM>Repeated Measure. Then put the columns which are your between-subjects factors into the ‘Between-Subjects Factors’ box.

#3170
RH
Member

Hi

Hope someone can help me with this! I need a way of doing a non-parametric version of the 2×2 factorial repeated-measures ANOVA, preferably in SPSS, R or Excel!. I’ve tried looking through the R documentation/ Wilcox’s book but they only seems to mention non-parametric versions of the 1-way repeated measures ANOVAs, or two-way mixed designs.

Has anyone done a non-parametric factorial repeated-measures ANOVA, and if so how is it done?

Thanks

Rob

#3169

Hi Professor Field –

Please forgive my ignorance in case it is blatant in this question.  I am a doctoral student and I have survey data from two scales (one five-point Likert scale on procrastination and the other dichotomous scale on delayed health-seeking behavior).  Is there any way to correlate the two even though they are different levels of data?  If so, can this be done in SPSS and how?  Finally, is it totally absurd to think a multiple regression could be done with this type of data?  I am interested if a model can be developed showing predictor variables from the procrastination and delay data?  Again, I apologize for my obvious lack of statistical knowledge and skill….I’m trying 🙂

Respectfully,

Lisa

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