Returns the mean (average value) of data (a sequence of numbers).
Returns the variance of data (a sequence of numbers).
Returns the standard deviation of data (a sequence of numbers).
Returns the median of data (a sequence of numbers).
Returns the skewness of data (a sequence of numbers).
Returns the kurtosis of data (a sequence of numbers).
Returns the correlation coefficient between data1 and data2, which must have the same length.