#### Background I am running a mixed linear model with four fixed predictors and (most of) their interactions. I am quite new to these models and I am trying to understand how I should interpret my results and whether I am using the correct approach to generate them. #### My Model My model contains two **factor** variables: (1) Group_Variable with *three* levels: 'Group_1_H', 'Group_2_L','Group_3_T'; (2) Variable_C with *two* levels: 'level1_O','Level2_S'. And it contains two **continuous** variables: Variable_A and Variable_B. The dependent variable is continuous. My prediction is that there will be an interaction between **Group_Variable** and **Variable_C**, whereby Group_1_H will show have a significantly different score on the outcome variable based on whether they are in condition 'level1_O' compared to 'level2_S' relative to the other two groups. Here is the model specification: ``` model <- my_outcome ~ lmerTest::lmer(Group_Variable * Variable_A * Variable_C + Group_Variable * Variable_B * Variable_C + (1 | ID_Variable), data = mydata) ``` Here is my output when I use the summary() function: [![Summary][1]][1] And here is the output when I use the Anova function from the car package: [![enter image description here][2]][2] And the post hoc pair-wise contrasts: |Group_Variable_pairwise |Variable_C_pairwise | estimate| SE| df| t.ratio| p.value| |:-----------------------|:-------------------|----------:|---------:|--------:|---------:|---------:| |Group_3_T - Group_1_H |level1_O - Level2_S | 0.0767201| 0.0156317| 3889.770| 4.907988| 0.0000029| |Group_3_T - Group_2_L |level1_O - Level2_S | 0.0156633| 0.0148981| 3889.107| 1.051362| 0.5444832| |Group_1_H - Group_2_L |level1_O - Level2_S | -0.0610568| 0.0163169| 3898.048| -3.741947| 0.0005430| #### Questions I have some questions based on this. 1. Is the Anova() function appropriate here? From what I have read online, people use the Anova function to compare models to find out whether the addition of a variable of interest significantly improves the model fit (e.g. https://stats.stackexchange.com/questions/500722/model-interpretation-in-r-anova-vs-summary-output). Can I also use it just to summarise the model I have specified and interpret the results? 2. Why are the p values for the interaction term (highlighted in both screenshots) different between the summary and Anova outputs? I have been trying to read about this online, and from what I understand the Anova is an omnibus test (i.e. compares several parameters at once) whereas the summary is step-wise. However, I would still expect there to be a significant result for 'Group_VariableGroup_1_H:Variable_CLevel2_S' in the summary as this is (I think?) essentially the same comparison as group 3 vs group 1 in the post hoc comparison table. If anyone could give me any advice I would hugely appreciate it as, based on what I have here, I currently do not know how to interpret my interaction. Many thanks in advance. [1]: https://i.sstatic.net/3HS9n.png [2]: https://i.sstatic.net/AQnOr.png