Compute the arithmetic, geometric and harmonic mean of the values of 11, 13, 4, 8, 8, 7, 9, 15, 10, 14, 8, 10, 8, 12, 9. Furthermore, calculate the median, lower and upper quartiles. Compute the variance and quartile range, quartile deviation, mean deviation, variance, sample variance, standard deviation, sample standard deviation, and coefficient of variation. Calculate the skewness and the kurtosis.