Uncertainty about normality (qqplot)

[SN131]

Hey everyone,
I've done several linear regression.
Now I would like to test if my residuals are normally distributed.
That is how my Q-Q Plots look like:

But I'm not sure what to make of the Q-Q Plots. Most of them are pretty much on the line, except for the beginning and ending.
What do you think?

[DavoWW]

Hi @SN131,
You can test the normality of your regression residuals as follows:

# See: https://cran.r-project.org/web/packages/olsrr/vignettes/residual_diagnostics.html
library(olsrr)
#> 
#> Attaching package: 'olsrr'
#> The following object is masked from 'package:datasets':
#> 
#>     rivers
model <- lm(mpg ~ disp + hp + wt + qsec, data = mtcars)

ols_plot_resid_qq(model)

ols_test_normality(model)
#> -----------------------------------------------
#>        Test             Statistic       pvalue  
#> -----------------------------------------------
#> Shapiro-Wilk              0.9366         0.0600 
#> Kolmogorov-Smirnov        0.1152         0.7464 
#> Cramer-von Mises          2.8122         0.0000 
#> Anderson-Darling          0.5859         0.1188 
#> -----------------------------------------------
ols_test_correlation(model)
#> [1] 0.970066

^{Created on 2021-04-20 by the reprex package (v2.0.0)}

[SN131]

Thank you for your answer.
But I think that my sample size is to large for analytic tests.
That's why I created graphics