Hello again everybody,

I am trying to run an ANCOVA test on R Shiny and one of the assumptions that need to be fulfilled in this test is that the residual variances should be similar for all groups (Homogeneity of variance). I have tried to use the function leveneTest() from the library(car). But I am not quite sure about it since it doesn't use the residual instead it uses the absolute value. This is how the app looks like:

and this is the code in R Studio:

```
# Output for Homogeneity of Variance ANCOVA
output$levTable <- renderPrint({
validate(
need(input$varAncovTest != "" && input$groupAncovTest != "" , "Undefined columns selected")
)
Data <- df()
if (is.null(Data)){return(NULL)}
DepVar <- Data[,input$varAncovTest]
IndVar <- Data[,input$groupAncovTest]
leveneTest(DepVar ~ IndVar,data=Data,center=mean)
})
```

The results should show a significant p-value and assumptions of equal error variances should be made. Is there any possibilities to measure the residuals instead of the absolute one? Thank you in advance!