AP Statistics Vocab

Categorical Variables

Place individuals into specific groups

Quantitative Variables

Takes on numerical values for which it makes sense to do arithmetic operations like adding and averaging. Fall into 2 categories: discrete & continuous

University Data

When conducting a study that looks at only 1 variable

Bivariate Data

When a study examines the relationship between 2 variables

Median

A simple measure of central tendency: to find, arrange observations smallest → largest: Odd # = middle number, Even # = average of 2 mid values

Mean

The average score: sum of individual scores divided by # of individuals

Standard Deviation

A numerical value used to indicate how widely individuals in a group vary: if individual observations vary greatly from the group mean, standard deviation is big, vice versa

standard deviation for a population = o

Standard deviation for a sample = s

Population

The total set of observations that can be made

Set

A well defined collection of objects

Sample

A set of observations drawn from a population

Symmetry

Used to describe the shape of data distribution: symmetric if it can be divided at the center and each half can mirror, a non symmetric distribution cannot

Unimodal distribution

Distributions with a clear peak

Bimodal distribution

Distributions with 2 peaks

Skewness

Fewer observations/higher values in the right = skewed right

Fewer observations/lower values on the left = skewed left

Uniform distribution

Refers to a probability distribution for which all of the values that a random variable can take on occur with equal probability

ex: a dice has 1/6 chance for each side, it has uniform distribution

in graphing: has no peaks: values in a set of data are equally spread across the range of the dataset

Gaps in Graphs

A graphic display where there are no distributions

Outlier

A data point that diverges greatly from the overall pattern of data

Dotplot

A type of graphic display used to compare frequency counts within categories or groups: made up of dots

Histogram

A graph made up of columns plotted on a graph: x axis equals a continuous: quantitative variable. Y - axis equals the size of the group defined by axis

Bar Charts vs. Histograms

Bar Chart: x - axis represents a categorical variable

Histogram: x-axis represents a quantitative variable - can be a single value or range

Stemplot

Used to display quantities data, generally small datasets

Boxplot

A type of graphic display used used to display patterns of quantitive data: splits dataset into quartiles

Quartiles

Divide a rank ordered dataset into 4 equal parts

Percentiles

Assuming a dataset rank ordered from smallest to largest: values that divide a rank ordered set of elements into 100 equal parts

Range

A simple measure of variation in a set of random variables

Range = Maximum value - Min value

Inrerquartile Range

A measure of variability based on dividing a dataset into quartiles

Interquartile range = Q3 - Q1

Parallel Boxplots

Data from 2 distributions are displayed on the same chart, with the same measurement scale

Parameter

A measurable characteristic of a population: such as a mean, proportion, or a standard deviation

A numerical value that describes a characteristic of a population

P = parameter = population

Proportion

Refers to the fraction of the total that possesses a certain attribute

Statistic

A numerical value that describes a characteristic of a sample

s = statistic = sample