CH3 - Numerical Measures Flashcards
Numerical value used as a summary measure for a sample
Sample Statistics
Numerical value used as a summary measure for a population
Population Parameter
Sample statistic used to estimate the corresponding population parameter
Point Estimator
A measure of central location computed by summing the data values and dividing by the number of observations
Mean
The mean obtained by assigning each observation a weight that reflects its importance
Weighted Mean
A measure of central location provided by the value in the middle when the data are arranged in ascending order
Median
A measure of location that is calculated by finding the nth root of the product of n values
Geometric mean
Measure of location, defined as the value that occurs with greatest frequency
Mode
Value such that at least p percent of the observations are less than or equal to this value. The 50th percentile is the median
Percentile
25th, 50th, 75th percentiles are referred to as…
Quartiles
A measure of variability, defined to be the largest value minus the smallest value
Range
Measure of variability, defined to be the difference between the third and first quartiles
Interquartile range
Measure of variability based on the squared deviations of the data values about the mean
Variance
Measure of variability computed by taking the positive square root of the variance
Standard Deviation
Measure of relative variability computed by dividing the standard deviation by the mean and multiplying by 100
Coefficient of variation
Shape of a data distribution. Negative to the left, positive to the right
Skewness
Computed by dividing the deviation about the mean(xi - x) by the standard deviation s
z-score
Used to make statements about the proportion of data values that must be within a specified number of standard deviations of the mean
Chebyshev’s theorem
Rule used to compute the percentage of data values that must be within one, two, and three standard deviations of the mean for data that exhibit a bell-shaped distribution
Empeirical rule
Unusually small or large data value
Outlier
