# contrasts

1. ### Polynomial (quadratic) contrasts: clarifications & inverted-U

Hello everyone, I am trying to see how the motor time of a response to a stimulus (DV: quantitative, continuous) evolves based on difficulty level of the task (IV: 8 levels, categorical). My hypothesis is that motor time will increase, then decrease (inverted U shape). I conducted a RM ANOVA...
2. ### Help with contrasts in MIXED MODELS

Hi! Hope you are all okay and safe! First of all, my English is not perfect, so if I said something wrong I am sorry for that. I am having troubles with the /test subcommand in linear mixed models I am working with a database in a long format, with 2 groups (intervention vs control) and 3...
3. ### Which ANOVA?

Hi there :) I am struggling to determine which would be the most appropriate ANOVA analysis to use for some work I am doing. I have 3 independent groups: control, CBT group, and CBT + antidepressant group. For each individual, there are 2 pieces of data- before and after treatment...
4. ### Defining Contrast Matrix

Suppose I have a binary Covariate X which is defined as X = \begin{cases} 1, & \text{if treatment group} \\ 0, & \text{if placebo group} \end{cases} The model is \mathbb E[Y] = \beta_0 + \beta_1X, where Y is a continuous random variable. If X=0, then \mathbb E[Y] =...
5. ### Default contrasts in ANOVA orthogonal?

Hi, I have a question regarding the default contrasts anova() uses R. As far as I understand, the default setting in anova is, that each group/treatment condition is compared to the baseline group. If I assume we have three treatment conditions A, B and C, and A is my baseline, I can now...
6. ### How to report a non-significant main effect with significant contrasts (LME)

Hi :wave:, Sorry for a lengthy first post, but I'm at my wits end :( I am using multilevel linear modelling with nlme's lme function to analyse a mixed design (2 categorical predictors, 1 a repeated measure with 5 levels, the other not repeated with 3 levels). From Andy Field's...
7. ### Contrasts (simple effects after interaction)

Hi, I need a help with SAS syntax regarding contrasts. I found after I ran GLM some interaction effects, but now I need to find out which independent variable has effect on my dependent variable. My advisor told me to do contrasts, but I am unskilled with it :( Design is 2x2 (type X color)...
8. ### Difficulty with creating orthogonal Linear Contrasts of interest

Hi out there - Is there a java program out there that can quickly give you all possible orthogonal Linear Contrasts after entering in a referential one? I would like to find all orthogonal LCs to these 6 coefficients. Any help would be greatly appreciated!! 1 -.25 -.25 -.25 -.25 0
9. ### 'Significant' product-term interaction but no significant simple main effect contrast

:wave: I'm conducting a conditional logistic regression to assess the association between a continuous predictor and a dichotomous outcome, adjusted for several covariates. I include product interaction terms between an exposure and a covariate in each of several models. In a few of these I...
10. ### what are contrasts?

Hi, I am doing homework for an assignment in statistics. I cannot get my mind up for what contrasts are. Anyone can explain that in simple words? thanks!
11. ### Interpreting "Within-subjects contrasts" in Mixed ANOVA

Greeting stats peers, After conducting a 2x2x(3) Mixed Model ANOVA, I am struggling to understand the SPSS output "Within subjects contrast" Specifically, - Factor B" (e.g., a sex-prime) exerted no main or interaction effect; - yet there was a significant AxBxC linear interaction in...
12. ### Binary DV and orthogonal contrasts

PLEASE HELP: Binary Dependent Variable and orthogonal contrasts HEEEEEEEEELLLLPPPPPP!!!!! The data I am trying to analyse has a binary dependent variable (1=yes, 0=no) and tow factors. Factor 1 is a treatment variable (treatment 1, 2, 3, 4) and Factor 2 is a manipulation (1=low , 2=high). I...
13. ### coding mixed contrasts

hello, i have problems coding the syntax for an anova with two factors, one between- and one within-subjects-factor (see syntax below). accordingly, there are 4 combinations of levels: wth_level1-btw_level1, wth_level2-btw_level1, wth_level1-btw_level2 and wth_level2-btw_level2. i am...
14. ### Contrasts: Possible in Factorial Anovas or only On-way Anovas?

Contrasts: Possible in Factorial Anovas or only One-way Anovas? I would like to set up some contrasts in my factorial anova so that I can look for possible interactions between factor A and the contrasts of factor B. From my reading, it doesn't seem to be possible. All of the guides seem to...
15. ### Contrasts in R for two-way and three-way interactions

I am new to using R and have just performed some mixed effect models which have significant 2-way and 3-way interactions. My question is now that I have a nicely constructed model, what next? Basically, I would like to perform pairwise comparisons for all of my interactions. My fixed...