Statistical Concepts and Market Returns Flashcards
Nominal Scale
Data is put into categories that have no particular order
Ordinal Scale
Data is put into categories that can be ordered with respect to some characteristic
Interval Scale
Differences in data values are meaningful, but ratios, such as twice as much or twice as large, are not meaningful
Ratio Scale
Ratios of values, such as twice as much or half as large, are meaningful and zero represents the complete absence of the characteristic being measured
Parameter
Any measurable characteristic of a population
Sample Statistic
Can describe characteristic of a sample
Relative Frequency
Percentage of total observations falling within a frequency
Cumulative Relative Frequency
for an interval is the sum of the relative frequencies for all values less than or equal to that interval’s maximum value
Histogram
Bar chart of data the has been grouped into a frequency distribution
Frequency Polygon
Plots the midpoint of each interval on the horizontal axis and the absolute frequency for that interval on the vertical axis and connects midpoints with straight lines
Quantile
general term for a value at or below which a stated proportion of the data in a distribution lies
Range
Difference between the largest and smallest values in a data set
Variance
Mean of squared deviations form the arithmetic mean or from the expected value of a distribution
Standard Deviation
Positive square root of the variance and is frequently used as a quantitative measure of risk
Chebyshev’s Inequality
States that the proportion of observations within k standard deviations of the mean is 1 - 1/(k^2) for all k > 1. It states that:
36% of observations lie within +/- 1.25 std. dev. of mean
56% of observations lie within +/- 1.5 std. dev. of mean
75% of observations lie within +/- 2 std. dev. of mean
89% of observations lie within +/- 3 std. dev. of mean
94% of observations lie within +/- 4 std. dev. of mean
Skewness
Describes the degree to which a distribution is not symmetric about its mean. Right-skewed distribution had positive skewness. Left-skewed distribution has negative skewness. Sample skew with absolute value greater than 0.5 is considered significantly different from zero
Positive Skew, Unimodal Distribution
Mean > Median > Mode
Negative Skew, Unimodal Distribution
Mean < Median < Mode
Kurtosis
Measures the peakedness of a distribution and the probability of extreme outcomes
Excess Kurtosis
Measured relative to a normal distribution, which has a kurtosis of 3. With an absolute value greater than 1 is considered to be significant
Leptokurtosis
Positive values of excess kurtosis (fat tails, more peaked). Probability of extreme outcomes are greater than for a normal distribution
Platykurtic Distribution
Negative values of excess kurtosis. Thin tails, less peaked
Arithmetic Mean Return
Appropriate for forecasting single period returns in future periods
Geometric Mean Return
Appropriate for forecasting future compound returns over multiple periods