AP STAT Graphical Displays (Theme 1)

Categorical frequency distributions

nominal or ordinal - level data that can be placed into categories

Histogram

displays data using vertical bars of various heights to represent the frequency of the classes

frequency polygon

a graph that displays data using lines that connect points plotted for the frequencies at the class midpoints

relative frequency graph

used when the proportion of data values that fall into a given class is more important than the actual number of data values

raw data

data collected in original form

frequency distribution

organization of raw data in table form using classes and frequencies

individuals

objects described by a set of data (ppl, animals, things)

variables

any characteristics of an individual

explanatory data analysis

helps examine data in order to describe their main features

Categorical

records which of several groups or categories

Quantitative

takes numerical values for which it

Distribution

tells us what values the variable takes and how often it takes these values (pattern of variation of a variable)

Dotplots

another name for line plot , which is used to graph

Stemplots

graphs quantitative data (for small data sets) using a stem and a leaf

overall pattern

a distribution that can be described by observing it’s center, spread, and shape

Deviations

difference between a value in a frequency distribution and a fixed number (as the mean)

Center

the value or description of the middle of the data

Spread

the extent of the data from the smallest to largest value

shape

the design of a distribution as symmetric or skewed

symmetric

right and left sides mirror each other

Skewed right

majority to the left

Skewed left

majority to the right

Outlier

any graph of data is an individual observation that falls outside the overall pattern of the graph

Time plot

of a variable plots each observation against the time at which it was measured

Trends

a long time upward or downward movement over time

Descriptive Statistics

summarize and describe known data (like mean, median, mode, charts), focusing on a specific sample.

Inferential Statistics

use sample data to make predictions, draw conclusions, and generalize findings to a larger, unknown population (using hypothesis tests, confidence intervals, regression)

Population

consist of the subjects being studied

Sample

a group of subjects selected from a population

Discrete variable

assume values can be counted

Continuous variable

infinite number of values between any two specific values