# Confusion on assessing the linearity assumption

This is for assignment. But i am not asking for hold my finger and guide me. Just asking something that is confusing me.

I am reading a chapter in which we are using gg_resX(mydata) from lindia package. The value of mydata was calculated from mydata <- with(my_centered_data, lm(y ~ x)).

The output of this is following graph

The author of the tutorial then went on to say that there is no non-linear pattern here. Even though, to me, it appears that there is kind of a sin wave ..

Now, here is another graph

Should i consider that there is no pattern here as well? Or should i call it out that there are outliers at the bottom of the graph?

I mean, I am not sure why author said in first graph that it is linear and because of that i am confuse at second one

• Can you post a link to the data itself, or just post the output of dput(data)? I cam see why you might observe a sinusoidal, but it's probably a bit too sparse and would be easy to "see" all kinds of things. – Robert Long Nov 15 '20 at 8:27
• i am not sure if i am allowed to do so :( as i said its for assignment – Em Ae Nov 15 '20 at 16:02
• What is being plotted in both of those figures ? Are they residuals from a model, or raw data ? – Robert Long Nov 15 '20 at 17:12