AP Stats Unit 1

Population

Entire group of items or individuals we want information about

Census

Collects data from every item or individual in a population

Sample

Subset of items or individuals in the population from which we collect data

Parameter

A number that describes some characteristic of a population

Statistic

A number that describes some characteristics of a sample

Observational unit

Item or individual described in a data set or statistical study

Variable

Characteristic that can take different values for different observational units

Categorical variable

Takes values that are labels, which place each item or individual into a particular group, called a category.

Quantitative variable

Takes number values that are quantities - counts or measurements

Discrete Quantitative variables

take a countable set of possible values with gaps between them on the number line

Continuous quantitative variables

take any value an interval on the number line

Distribution

What values the variable takes and how often it takes each value

Frequency table

Shows the number of observational units having each value of a a variable.

Relative frequency table

Shows the proportion or percentage of observational units having each value a variable

Pie chart

graph of data for one categorical variable that displays each category as a slice of the "pie." The area of each slice is proportional to the category frequency or relative frequency.

Side by side bar chart

graph of data for one categorical variable in each of two or more groups that displays a separate bar corresponding to each group for every category. The height of each bar shows the category frequency or relative frequency within that group.