AP Statistics Unit 1 (copy)

variable

holds information about the same characteristic for many subjects

categorical data

Data that consists of names, labels, or other nonnumerical values

quantitative data

where the data collected is numerical and it makes sense to use it for numerical operations

frequency table

lists the categories for a categorical variable and displays the counts for each category

relative frequency table

lists the categories for a categorical variable and displays the percentages for each category

stem and leaf plot

A method of graphing a collection of numbers by placing the "stem" digits (or initial digits) in one column and the "leaf" digits (or remaining digits) out to the right.

dotplot

a display for either kind of data that uses a dot to represent each individual in the data set

symmetric distribution

a distribution whose shape is unimodal and each side is roughly a mirror image of the other

left skewed distribution

a distribution that has a concentration of data on the upper end and the tail on the left

right skewed distribution

a distribution with a concentration of data on the lower end and the tail on the right

outliers

values that fall outside the overall pattern of the data

mean

the average of the data values

median

the value in the center of an ordered data set

range

the maximum data value minus the minimum data value

first quartile

the value where 25 % of the data fall below it in an ordered list

third quartile

the value where 75% of the data falls below it in an ordered list

Interquartile Range (IQR)

the third quartile minus the first quartile

percentile

the place in the data where a certain percentage of the data falls below that value

5 number summary

includes the minimum, first quartile, median, third quartile, & the maximum

boxplot

a display for quantitative data that graphs the five-number summary on an axis and shows outliers if they exist

variance

the standard deviation squared, it is a measure of spread

resistant

word to describe when values that are not strongly affected by extremes

Conditional Distribution

a distribution of values for one variable that exists when you specify the values of other variables

Pie Graph

used to show parts of a whole

Bar Graph

a graph that uses vertical or horizontal bars to show comparisons among two or more items

Segmented Bar Graph

Used to compare the distribution of a categorical variable in each of several groups.

Histogram

a display for quantitative data that uses adjacent bars to represent counts or percentages of values falling in each interval

Measure of center

mean, median, mode

Measures of Spread

Range, Interquartile Range, Standard Deviation

How to describe a distribution

C-Context S - Shape O - Outliers C - Center S - Spread

Standard Deviation

a measure of variability that describes an average distance of every score from the mean

marginal distribution

Distribution of values of that variable among all individuals described by the table.