Quartiles, quintiles, deciles, and percentiles are values or cut points that partition a finite number of observations into nearly equal-sized subsets. The number of partitions depends on the type of cut point involved.

Measures of dispersion are used to describe the variability or spread in a sample or population. They are usually used in conjunction with measures of central tendency such as the mean and the median. These are the range, variance, absolute…

Skewness refers to the degree of deviation from a symmetrical distribution, such as the normal distribution. A symmetrical distribution has identical shapes on either side of the mean. Distributions that are asymmetrical have unequal shapes on either side of the…

A unimodal distribution is a distribution that has one clear peak. The values increase first, rising to a single highest point where they then start to decrease. A unimodal distribution can either be symmetrical or nonsymmetrical. A symmetrical distribution is…

Kurtosis refers to measuring the degree to which a given distribution is more or less ‘peaked’ relative to the normal distribution. The concept of kurtosis is very useful in decision-making.  In this regard, we have 3 categories of distributions:

Both arithmetic return and geometric return are methods commonly used to calculate the yield on a given investment. However, the return that really matters is the geometric return, not the arithmetic return. A good understanding of the difference between the…

Probability is a measure of the likelihood that something will happen. We usually express probabilities as percentages, from 0 (impossible to happen) to 100% (guaranteed). In fact, we can express almost any event as a probability, e.g., the likelihood that…

Defining properties of a probability refer to the rules that constitute any given probability. They are outlined below.