Which concept describes a distribution's peakedness or flatness relative to a normal curve?

• A. Kurtosis
• B. Skewness
• C. Variance
• D. Range

Answer: (A)

Kurtosis describes how peaked or flat a distribution is compared with a normal curve. If a distribution has a sharper peak and fatter tails than the normal curve, it’s leptokurtic. If it has a flatter peak and thinner tails, it’s platykurtic. The normal distribution is considered mesokurtic, serving as the reference point. In many cases kurtosis is discussed as excess kurtosis (kurtosis minus 3), so the normal curve has an excess kurtosis of 0. This concept focuses on the shape around the center and the tails, rather than on overall spread. Skewness, in contrast, is about asymmetry between the two sides of the distribution; variance and range describe dispersion, not peak shape.