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Can I use games-howell post hoc for specific pairwise comparisons?

I will provide more context: My initial intent was conducting a one-way ANOVA and then follow up with planned comparisons (contrasts). Sadly, the homogeneity of variances assumption was violated, and ...
Guy's user avatar
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Planned comparisons: t-tests vs multiple regression analysis [closed]

I ran an experiment with three groups (one control, two experimental). Now, I am analysing the results. I ran: a regression analysis (with dummy coded groups, control group put as the contrast) two t-...
user1306775's user avatar
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Planned comparison in the absence of significant interaction

this is a topic that has been discussed in other posts, but there was never a direct answer to my question. I have a dataset whereby my dependent variable is predicted by three categorical factors of ...
SinC's user avatar
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Calculating percentage change from emmeans

A related question was asked on this thread How to calculate percentage difference of geometric means with emmeans?, but I still need some help. Instead of calculating the absolute difference between ...
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Confusion for 2-way Anova in 2x2 experimental design with planned comparisons

I am really confused regarding 2-way Anovas. I think I did not understand something properly. Let's say I have a 2x2 experiment design with 2 factorial variables (For the sake of an example let's say ...
Cookie's user avatar
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Repeated measures ANOVA modeling question

I have a (to me) complex experimental design I'm working on pre-registering and I want to make sure I'm approaching the model correctly. I've attempted to offer an illustration of the design below. I ...
Teresa's user avatar
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2 votes
1 answer
125 views

Planned comparisons significant but interaction non-significant

I ran a simple linear mixed model using lmer on a dataset for participants who had been randomly assigned to one of two conditions and were measured at baseline, ...
Biscuity's user avatar
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How to perform non-orthogonal planned contrasts (and a-priori power-analysis for this)?

I have four treatment groups (A, B, C, D) and measure three dependent variables (X, Y, Z). My hypotheses are that each dependent variable is strongest in one of the treatment groups, compared to all ...
Annette M's user avatar
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Planned contrasts to test a priori hypotheses

I am planning a study with three between conditions. Let's say "Experimental group" vs. "Control group" vs. "Placebo group". And I have a numeric outcome "DV" ...
Y45H's user avatar
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541 views

Differences between ANOVA post-hoc tests and planned contrasts?

The source below seems to suggest that ANOVA post-hoc tests are simple t-tests (or "pretty much so") and therefore that planned contrasts are more powerful. This was also my understanding ...
rempsyc's user avatar
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Analysis sense check: preregister planned contrasts which we wish to conduct even if associated ANOVA is nonsignificant?

I could use a sense check on my analysis plan for an experimental study which has not yet been run; I will preregister it once I am confident that it is reasonable. There are seven between-...
Gabriel's user avatar
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Is it appropriate/acceptable to do planned comparisons for data that will be submitted to a scientific journal?

I am currently analyzing data for an age-related neuroscience study with a 2x2 factorial design (treatment (2 levels) x age (2 levels)) yielding 4 total groups: Young untreated, Young treated, Aged ...
user120818's user avatar
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0 answers
166 views

Multiple comparisons among orthogonal contrasts

Do I need to make an alpha adjustment when testing planned orthogonal contrasts. While the contrasts are independent the same residual error is used. The author of a well regarded textbook on ...
TTemplln's user avatar
2 votes
1 answer
1k views

Should I use the package "emmeans" for planned comparisons? Or should it be used only for post-hoc tests?

Because "emmeans" looks at all pairwise comparisons, I am asking myself if I should use the package for planned comparisons (I have hypotheses about the differences between certain groups). ...
harico287's user avatar
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102 views

Why do we need the package "emmeans" to compare between groups? Why don't we just calculate the confidence intervals?

I am conducting a Poisson regression to find differences between universities in 5 regions regarding the number of crimes occured there. The output: ...
harico287's user avatar
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Pairwise contrasts for logistic regression in emmeans, back-transform or not?

I ran a mixed effects logistic regression in R (glmer). The model identified a significant three-way interaction that I am interested in decomposing using post-hoc multiple comparison in emmeans. In ...
Nick Pardikes's user avatar
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1 answer
661 views

Repeated Measures MANOVA Planned Comparisons & Profile Analysis

I'm conducting a repeated measures MANOVA with one IV (4 conditions) and 2 DV's. My participants have taken each condition. Assuming the MANOVA and univariate tests are significant, I would like to ...
statshelpneeded's user avatar
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1 answer
390 views

Combining customized contrasts + nested ANOVA (?)

I would like to get some advice on running a customized contrast analysis. I have looked at a few vignettes and I think I get the basic idea, but I'm not sure how to adapt them for my purpose. To ...
intasker's user avatar
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644 views

Can planned contrasts in ANOVA be one tailed tests?

I have an experiment with 3 within-subject conditions: A, B and C. My dependent variable is reaction time. I am interested in comparing A to B and A to C. Using ...
Rtist's user avatar
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2 votes
1 answer
624 views

ANOVA - significant main effect, no significant interaction. What to do next? planned comparison / post-hoc tests / simple effects?

I conducted a two-way ANOVA, with perceived diagnosticity, i.e. the ability to evaluate haptic properties of a product, as the dependent variable and sound manipulation (congruent, incongruent and no-...
Jens Stach's user avatar
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1 answer
449 views

Negative Binomial „Ancova” with planned contrasts

My DV is count, obtained from psychological questionnaire (14 questions with options ”Yes”/”No”, each yes is 1 point, thus overall result is count of yeses). I’ve checked that Poisson distribution ...
Waran's user avatar
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how can i do a priori (planned) contrasts for a 2 factors with interaction binomial GLM?

i´m new with R and i have a question to do. i´m doing a study on seed germination and i have trouble doing a priori contrasts for a GLM analysis. My response variable is proportion of seeds ...
Dario Fergnani's user avatar
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1 answer
51 views

Comparing groups with different sample sizes

I have some data about network outages in two companies, by the type of machines they have: ...
ThatGuy's user avatar
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1 vote
0 answers
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Reporting weights used in a priori planned comparisons APA style

My lecturer wants us to report in APA style the weights we used in a planned orthogonal comparison. I can't find this information anywhere, not in previous journal articles or APA publications. Can ...
Jane's user avatar
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1 answer
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Multiple planned comparisons of frequencies (based on a binary DV and multiple IV's)

I'm looking for the most appropriate way to to conduct multiple planned comparisons of frequencies. I conducted an experiment in which participants could come from one of two groups, 'Group A' and '...
Suggy's user avatar
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1 vote
2 answers
324 views

Is a planned contrast significant if p is lower than .05 with no correction for multiple comparisons but higher than .05 with the correction?

I conducted a 2 x 4 within-subjects design experiment. I presented participants with unpleasant and neutral pictures and asked them to cope with their emotions in four different ways. Therefore, the ...
Karolina's user avatar
1 vote
0 answers
58 views

Planned contrast through factor-based vs. model-parameter-based approach

I have two questions concerning planned contrasts: I would like to know how factor-based contrasts (obtained through an interaction term) compare to model-paramter-based contrasts (obtained by ...
Flo's user avatar
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1 vote
1 answer
63 views

ANOVAS and Planned Comparisons

I'm fairly new to stats and we have been asked to conduct our own one way ANOVA's for class. Our first hypothesis is that gender will effect exercise. Our second is more one tailed, Men will ...
B.hunter's user avatar
2 votes
0 answers
109 views

Bayesian planned orthogonal contrasts, can one just average two means?

I have a dataset with three levels of one independent variable, repeated measures. To simplify, I have two planned contrasts to perform: High Treatment & Low Treatment combine, vs No Treatment ...
Doctor David Anderson's user avatar
1 vote
1 answer
554 views

Planned comparisons and experiment-wise error rate in factorial experiments

When using planned comparisons in the context of factorial experiments is it still necessary to compensate for the inflation of the experiment-wise error rate? My planned comparisons involve 4 ...
Rooirokbokkie's user avatar
1 vote
1 answer
327 views

Significant omnibus f-test but planned comparison testing showing no evidence of effect

i'm testing the relationship between four age groups of teachers on their perceived level of job security. I've run an omnibus f-test on some data, 240 subjects- no examples of any skewness, and it ...
Oscar's user avatar
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1 vote
0 answers
660 views

Independent t test significant but post-hoc planned analysis not

I was analysing two sets of data. In most cases for the study post hoc planned comparisons identified significance (<0.05), however for one sample, this was not achieved. However an independent t ...
Chris Wood's user avatar
2 votes
2 answers
454 views

When an effect size has to be considered sufficiently large?

I submitted a paper in which I analyzed the data by a mixed-design ANOVA. I reported generalized eta squared as effect size. After significant interactions, I conducted planned comparisons. A reviewer ...
this.is.not.a.nick's user avatar
1 vote
1 answer
154 views

Partially orthogonal planned comparisons

I am comparing 8 means and want to set up a planned comparisons, rather than having my Bonferroni adjustment become overly-conservative in a post-hoc. For my groups I need to make a total of 16 ...
Phillip's user avatar
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4 votes
1 answer
4k views

Non-orthogonal planned comparisons: How to correct alpha?

I have a data set containing three groups (A, B, C). Group A and Group B have undergone two different types of training designed to improve the same thing. Group C is my control group with no ...
JamesC's user avatar
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2 votes
0 answers
213 views

One-way independent ANOVA where I expect two levels to be very similar and the other to be different. What's the right test?

I'm expecting Groups 1 & 2 to be very similar and Group 3 to be different. I'm using a very large data set and feel that power won't be an issue. Initially I felt that I'd then be expecting a ...
user1205901 - Слава Україні's user avatar
2 votes
2 answers
2k views

A priori comparisons in a repeated measures design

I'm interested in finding out more about the use of a priori planned contrasts within a one-way repeated measures ANOVA design. Predictions: Grps 2+3 < Grp 1 Grp 2 < Grp 3 My questions are: ...
user26473's user avatar
3 votes
2 answers
2k views

Correcting for multiple comparisons on planned contrasts with an ANCOVA

I have done an experiment with 7 treatment conditions designed to reduce alcohol intake, and a control condition. The dependent variable is alcohol intake after treatment, and I have run an ANCOVA ...
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