Why Shapiro Wilk Test?

Shapiro-Wilks Normality Test. The Shapiro-Wilks test for normality is one of three general normality tests designed to detect all departures from normality. It is comparable in power to the other two tests. The test rejects the hypothesis of normality when the p-value is less than or equal to 0.05.

What is the purpose of Shapiro-Wilk test?

The Shapiro–Wilk test, which is a well-known nonparametric test for evaluating whether the observations deviate from the normal curve, yields a value equal to 0.894 (P < 0.000); thus, the hypothesis of normality is rejected.

Why do we use Shapiro test for residuals?

While a residual plot, or normal plot of the residuals can identify non-normality, you can formally test the hypothesis using the Shapiro-Wilk or similar test. The null hypothesis states that the residuals are normally distributed, against the alternative hypothesis that they are not normally-distributed.