The Shapiro-Wilk test tests if a sample comes from a normally distributed population. The test is biased by sample size, so it may yield statistically significant results for any large sample.
This node is applicable for 3 to 5000 samples, but a bias may begin to occur with more than 50 samples.
More information can be found at Shapiro–Wilk test on Wikipedia.
Hypotheses:
H 0 : sample comes from a normally distributed population.
H A : sample does not originate from a normally distributed population.