Hey guys,
First of all, I would like to apologize for the question I'm gonna ask regarding the fact, that I am absolute beginner in statistics.
Currently I'm trying to test some hypotheses in Rstudio using Simple Linear Regression, as I am aware that before interpreting results of my model I have to provide verification of assumptions that should be meet within the model.
Unfortunately, one of the key assumption is not very clear for me, could someone explain please?
"The mean of the residuals should be equal to zero."
I have no clue which of the residuals I should sum and then divide by number of items. I tried every possibility but it's never zero (I tried it also within other models). So basically my conclusion is that I'm doing something wrong.
I tried to plot residuals and it seems fine for me.
I would be very thankful for any advice or explanation.
Thank you very much.

First of all, I would like to apologize for the question I'm gonna ask regarding the fact, that I am absolute beginner in statistics.
Currently I'm trying to test some hypotheses in Rstudio using Simple Linear Regression, as I am aware that before interpreting results of my model I have to provide verification of assumptions that should be meet within the model.
Unfortunately, one of the key assumption is not very clear for me, could someone explain please?
"The mean of the residuals should be equal to zero."
I have no clue which of the residuals I should sum and then divide by number of items. I tried every possibility but it's never zero (I tried it also within other models). So basically my conclusion is that I'm doing something wrong.
I tried to plot residuals and it seems fine for me.
I would be very thankful for any advice or explanation.
Thank you very much.


