AP STATISTICS UNIT 1 VOCABULARY

variable

variable

characteristic that changes from one individual to another.

distribution

describes what values the variable takes and how often it takes each value

dot plot

a dot plot shows each data value as a dot above its location on a number line

Histogram

a histogram divides the range of data into classes of equal width.

Adjacent bars should touch

Side by Side bar graph

displays the distribution of one categorical variable in each of two or more groups

-include color keys

-use relative frequencies

Misleading graphs

includes 3d effects, weird scaling, look at the scales to see if they’ve been distorted. Avoid making bars of a bar graph with pictures whose height and width vary.

Bar graph

shows each category as a bar. the heights of the bars show the category frequencies or relative frequencies.

Pie chart

shows each category as a slice of a pie. the areas of the slice are proportionate to the category frequencies or relative frequencies.

A quantitative variable

takes numerical values that count or measure some characteristic of each individual

discrete variable

a quantitative variable that takes a countable set of possible values with gaps between them on a number line

Continuous variable

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

Frequency

a frequency table shows the number of individuals having each value

relative frequency

shows the proportion or percentage of individuals having each value

categorical variable

takes values that are labels

statistics

the science and art of collecting, analyzing, and drawing conclusions from data.

individuals

people, animals, or things described by a set of data

bimodal

two clear peaks

multimodal

more than two peaks

uniform

even throughout

SOCS

S-Shape

O- Outliers

C-Center

S-Spread

stemplots

shows each data value separated into two parts

symmetric

right side of the graph mirrors the left

skewed right

if the right side of the graph is much longer than the left

skewed left

if the left side is longer than the right

“splitting” stems

essentially just trying to keep the stem plot more clean, splitting the data into 2 to make it more even.

The split stem and leaf plot separates each stem into many stems based on its frequency

Effect on mean and median :Skewed left

mean<median

Effect on mean and median :Skewed right

mean>median

Effect on mean and median :symmetric

mean=median

Standard Deviation

measures the spread of a data distribution. it measures the typical distance between each data point and the mean.

Quantitative graphs

-dot plots

-stem and leaf plots

-histograms

categorical graphs

-bar graphs

-pie charts