Numerical Descriptions of Shape

Table of descriptive statistics for standard grade bearings — Figure 1. Descriptive statistics, standard grade bearings

The Descriptives table is pivoted so that Alloy is in the layers of the pivot table, with standard bearings displayed first. The mean, trimmed mean, and median are nearly equal, and the skewness and kurtosis statistics are close to 0. This is strong evidence that heat resistance in standard bearings is normally distributed.

Table of descriptive statistics for premium grade bearings — Figure 2. Descriptive statistics, premium grade bearings

The premium bearings tell a different story. The mean is higher than either the trimmed mean or the median; outliers or extreme values are pulling it upward. The skewness and kurtosis statistics also provide evidence of disproportionate values at the upper tail of the distribution.