# Questions tagged [main-effects]

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### Why type III sum of squares is not recommended to use when there is significant interaction?

I did notice that in the following example, I obtained a insignificant main effect for treatment when including interaction, although the treatment is clearly effective. Any intuitive explanation? ...
12 views

### Factor Levels in a Two-Way ANOVA

I'm trying to figure out the explanations of the Effect Plots below. I believe I have figures out Figure 9a, but the explanation for Figures b, c, and d given in the textbook I do not comprehend. Any ...
9 views

### Given a specific model how would you find the possible effects and interactions of the factors?

I am looking for contaminations on two different beaches N and S at two different times T1 and T2. Where it is suggested that Beach N has a higher risk of contamination than beach S and the levels ...
189 views

### Main effect vs simple effect

In the following linear model: $y = \beta_0 +\beta_1 x_1 +\beta_2 x_2 + \beta_3x_1x_2 + \epsilon$ what are called $x_i$? The term $x_1x_2$ is the interaction. In ANOVA, $x_i$ are named "main ...
15 views

### Is a "deviance table" equivalent to the type 2 or type 3 ANOVA?

I was taught, that ANOVA assesses the main effects and interaction effects of a linear model. In other words, it jointly tests appropriate model (with categorical IVs) parameters, telling us, if all ...
18 views

### Using Orthogonal Main Effects Plan to select profiles for conjoint analysis

I am trying to create a code in Python to select orthogonal profiles given some attributes and levels. For eg: ...
7 views

### Prediction of a null-effect in the interaction but a main effect of condition

Let's assume I have 2 groups of subjects (A, B) and I test these groups in a task where I measure reaction time (RT) in two conditions (C1, C2), which I will analyze with an Anova. Is it legit to ...
157 views

### Three-way MANOVA Interpretation

I'm interpreting a three-way MANOVA as part of my research, and have come across an interpretation challenge, with three independent variables (Factor A, Factor B, and Factor C) and two dependent ...
15 views

### The procedure of adding interaction terms in regression models

What is the more sensible way to add interaction terms in regression models? I have a basic model which includes only the main effects. To add interactions to the basic model, do I add all of them at ...
216 views

### Why are Simple Effects only used when the interaction is significant?

I have conducted a 2-way ANOVA and obtained a significant Main Effect in IV1 and IV2, but a non-significant interaction. Following that, I have analyzed IV1 using a test for Simple Effects and ...
58 views

### lmer Dropping levels from summary information in models with main effect and interactions

First off, here are my models: ...
34 views

### Interaction effect in logistic regression

I have applied logit model, where my dependent variable is Emp (Employment) 1 if employed otherwise 0, and used level of education and Health status as independent variables where: Education consist 6 ...