READING 3 STATISTICAL MEASURES OF ASSET RETURNS Flashcards
Identify the center, or average, of a dataset. This central point can then be used to represent the typical or expected value in the dataset.
Measures of a central tendency
What is the most widely used measure of central tendency?
Arithmetic mean
the sum of all the values in a sample of a population, ΣX, divided by the number of observations in the sample, n. It is used to make inferences about the population mean.
Sample mean which is an example of arithmetic mean
Midpoint of a data set, where the data are arranged in ascending or descending order.
Median
When is the median better measure of central tendency than the mean?
When the mean is affected by outliers
What is the median return for five portfolio managers with a 10-year annualized total returns record of 30%, 15%, 25%, 21%, and 23%?
23%
What is the median return for five portfolio managers with a 10-year annualized total returns record of 30%, 15%, 25%, 21%, and 23%
Suppose we add a sixth manager to the previous example with a return of 28%. What is the median return?
24%
The value that occurs most frequently in a dataset
Mode
When a distribution has one value that appears most frequently, it is said to be
Unimodal
When a dataset has two or three values that occur most frequently, it is said to be
Bimodal and Trimodal
What is the mode of the following dataset?
Dataset: 30%, 28%, 25%, 23%, 28%, 15%, 5%
28%
True or false
For continuous data, such as investment returns, we typically do not identify a single outcome as the mode. Instead, we divide the relevant range of outcomes into intervals, and we identify the modal interval as the one into which the largest number of observations fall
True
In some cases, a researcher may decide that outliers should be excluded from a measure of central tendency, what techniques should he use?
Trimmed and Winsorized mean
A technique that excludes a stated percentage of the most extreme observations. A 1% mean, for example, would discard the lowest 0.5% and the highest 0.5% of the observations
Trimmed mean
A technique that instead of removing the extreme values, this method replaces them with the nearest values that are not considered outliers. For example, in a 90% mean, the lowest 5% of values are replaced with the 5th percentile value, and the highest 5% of values are replaced with the 95th percentile value. Then, the mean is calculated using these adjusted values
Winsorized mean
Is the general term for a value at or below which a stated proportion of the data in a distribution lies. Or values that divide a dataset into equal parts. They help in understanding the distribution of data
Quantile
The distribution is divided into quarters
Quartile
The distribution is divided into fifths
Quintile
The distribution is divided into tenths
Decile
The distribution is divided into hundredths (percentages)
Percentile
Note that any quantile may be expressed as a percentile. For example, the third quartile partitions the distribution at a value such that three-fourths, or 75%, of the observations fall below that value. Thus, the third quartile is the 75th percentile
What is the difference between the third quartile and the first quartile (25th percentile) known as?
Interquartile range
What is defined as the variability around the central tendency?
Dispersion
True or false
The common theme in finance and investments is the tradeoff between reward and variability, where the central tendency is the measure of risk and dispersion is the measure of reward
False
Correction: The central tendency is the measure of reward and dispersion is the measure of risk
Relatively simple measure of variability, but when used with other measures, it provides useful information. The distance between the largest and the smallest value in the dataset
Range
What is the range for the 5-year annualized total returns for five investment managers if the managers’ individual returns were 30%, 12%, 25%, 20%, and 23%?
Range = 30 − 12 = 18%