Topic 2 (Summarizing Distributions)

mean (x with a line over it)

an arithmetic range

median (M)

the middle of a set of data when arranged in order from least to greatest

quartiles

segments of the data in groups of 25% intervals

Parameter

a characteristic or measure obtained by using all the data values for a specific population

variability

a numerical summary of a distribution reporting its center and spread

5 number summary

a useful numerical description of data contained in the set ( Min, Q1, M, Q3, Max )

box plot

the graph of the distribution of numbers contained in the 5 number summary

statistic

a characteristic or measure obtained by using the data values from a sample

outlier

an observed value that is more than (1.5 x IQR) below Q1 or above Q3; anything that does not meet the overall pattern

modified boxplot

a boxplot that plots outliers as isolated points

degrees of freedom (n-1)

the number of free choices left after a sample statistic is calculated

variance (s^2)

the average of the squares of the deviations of the observations from their mean

standard deviation

measures spread by looking at how far the observations are from the mean

interquartile range (IQR)

the difference between Q3 and Q1, which is 50% of the data distribution

resistant

the non-changing characteristic of the median in response to a change of extreme observations

range

the difference from the largest and smallest observations (full spread of data)

non-resistant

the mean is sensitive to the influence of extreme observation