Percentage of items correct. Number of students taking the exam. Average test score. It is more likely the observed score falls within a range of values near the true score. Indicates deviation of the distribution from a normal distribution.
Positive skewness indicate scores cluster toward the low end of the distribution.
Negative skewness indicate more peaked distribution scores cluster toward the high end of the distribution. A measurement of relative peakedness of the distribution. A normal distribution will have a Kurtosis of zero. Negative Kurtosis indicates a distribution flatter than the normal distribution. Positive Kurtosis indicates a more peaked distribution.