Chapter 3 Flashcards
measure of “average” computed by adding together all the values in the data set and dividing by the number of observations
arithmetic mean
μ (pronounced “mew”) - parameter computed using data from all the individuals in a population
population arithmetic mean
“x-bar” - statistic computed using data from individuals in a sample
sample arithmetic mean
value that lies in the middle of a data set when arranged in ascending order
median
numerical summary of data is ___ if outliers do not affect it substantially
resistant
observation that occurs most frequently in a data set
mode
the degree to which data values are spread out
dispersion
simplest measure of dispersion - difference between the largest and smallest data value
range
square of the standard deviation (expressed in units squared)
variance
if a distribution is roughly bell shaped, approximately 68% of data will be within 1 standard deviation of mean, 95% will be within 2 standard deviations, and 99.7% will be within 3 standard deviations
The Empirical Rule
represents the distance that a data value is from the mean in terms of the number of standard deviations - subtracting mean from value, then dividing by the standard deviation
z-score
divide a set of data into 100 parts, in ascending order - at the 15th ___, 15% of observations are less than or equal to the value
percentiles
divide data sets into four equal parts - 1st and 3rd found by determining medians
quartiles
range of the middle 50% of observations in a data set (Q3 minus Q1) - resistant measure of dispersion
interquartile range (IQR)
extreme observations that skew data (outside of the “fences”)
outliers
