if the sample size is small (n < 2,000), run Shapiro-Wilk test
shapiro.test(data)
otherwise (n > 2,000), run Kolmogorov–Smirnov test
ks.test(data,"pnorm",mean=mean(data),sd=sd(data))
either way, if the output exceeds the level of significance (p), the data set can be considered as normal distribution.
