AP Stat Unit 1 Vocab

Unit 1 of AP STAT

individual

individual

an object described in a set of data; can be people, animals, or things

categorical variable

assigns labels that place each individual into a particular group

quantitive variable

takes number values that are counts or measures

discrete variable

a quantitative variable that takes a fixed set of possible values with gaps in between them (whole numbers)

continuous variable

a quantitative variable that can take any value in an interval on the number line

marginal relative frequency

percent or proportion of individuals that have a specific value for one categorical variable

joint relative frequency

percent or proportion of individuals that have a specific value for one categorical variable and a specific value for another categorical variable

conditional relative frequency

percent or proportion of individuals that have a specific value for one categorical variable among individuals who share the same value of another categorical variable

side-by-side bar graph (definition)

displays the distribution of a categorical variable for each value of another categorical variable; the bars are grouped together based on the values of one of the categorical values placed side by side

segmented bar graph (definition)

displays the distribution of a categorical variable as segments of a rectangle, with the area of each segment proportional to the percent of individuals in the corresponding category

mosaic plot (definition)

a modified segmented bar graph in which the width of each rectangle is proportional to the number of individuals in the corresponding category

association

if knowing the value of one variable helps us predict the value of the other

outlier

individual value that falls outside the overall pattern of a distribution

statistic

number that describes some characteristic of a sample

parameter

number that describes some characteristic of a population

resistant

if a statistical measure is not sensitive to extreme values

standard deviation

measures the typical distance of the values in a distribution from the mean

quartiles

divide the ordered data set into four groups having roughly the same number of values

interquartile range

the distance between the first and third quartiles of a distribution

percentile

the value with p% of observations less than or equal to it

cumulative relative frequency graph

plots a point corresponding to the percentile of a given value in a distribution of quantitative data

standardized score (z-score)

tells how many standard deviations from the mean an observation falls, and in what direction

Normal distribution

described by a symmetric, single-peaked, bell-shaped density curve called a Normal curve

empirical rule

in a Normal distribution with mean μ and a standard deviation σ: approx. 68% of observations fall within σ or the mean μ; approx. 95% of observations fall within 2σ of the mean μ; approx. 99.7% of the observations fall within 3σ of the mean μ

standard Normal distribution

the Normal distribution with mean 0 and standard deviation 1

side-by-side bar graph (image)

segmented bar graph (image)

mosaic plot (image)