AP STAT Topic 2 Summarizing Distributions

mean

an arithmetic average

median

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

Quartile

segments of the data in groups of 25% intervals

Five number summary

a useful numerical description of a distribution of data contained in a set

Boxplot

The graph of the distribution of numbers contained in the five number summary

Modified boxplot

a boxplot that plots outliers as isolated points

Variance

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

Standard deviation

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

Range

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

Nonresistant

the mean is sensitive to the influence of extreme observation

Resistant

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

Interquartile Range

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

Outlier

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

Degrees of freedom

the number of free choices left after a sample statistic (n-1)

Variability

a numerical summary of a distribution reporting its center and spread

Statistic

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

Parameter

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