Displaying and Describing Distributions Chapter 1 Displaying and Describing Distributions

Statistics – what is it? Individuals – are the objects described by a set of data; people/animals/etc. Variables – any characteristic of an individual; it can take different values for different individuals

ASK??? Who? What? Why? What individuals…. How many ….. Variables… Exact definitions… Units Why?

Types of Variables Categorical Variable – records which group or category an individual belongs to Single, senior, 18-24 yr olds Quantitative Variable – takes numerical values for which arithmetic operations such as adding and averaging make sense Salary, weight, age

Problem 1.1 Page 7 What are the individuals in this data set? For each individual, what variables are given? Which of these variables are categorical and which are quantitative?

Distribution – tells us what values the variable takes and how often it takes the values.

Types of Graphs Bar Graph – pg 9 Pie Charts – pg 9 Dotplots – pg 11 Stem & Leaf – pg 13 Histogram – pg 19 Time plot – pg 31 Box & Whisker – pg Categorical Variables

Problem 1.8 (a) page 17

Caffeine Content (mg) per 8-ounce serving of various soft drinks Key: 3|5 means the soft drink contains 35 mg of caffeine per 8-ounce serving.

Caffeine Content (mg) per 8-ounce serving of various soft drinks Key: 3|5 means the soft drink contains 35 mg of caffeine per 8-ounce serving.

Describe the overall pattern of a distribution Center Unusual (outliers) Spread Shape

Shape … Symmetric – distribution is symmetric when left and right sides of histogram are approximately mirror images of each other Skewed to the right – right side is LONGER than the left Skewed to the left – left side is LONGER than the right

Problem 1.8 (b) page 17

Histograms Most common graph of the distribution of ONE quantitative variable

Types of Variables Identify the type of variable Types of Variables Identify the type of variable. If possible, describe the shape of the distribution. 1) The number of times out of 100 draws that each suit is drawn from a deck if a single card is drawn at random & replaced 2) The heights of male students in your school 3) The income of adults in your city 4) The color of M&M candies selected at random from a bag 5) The number of speeding tickets each student in AP Statistics has received 6) The number of pairs of shoes owned by students in AP Statistics 7) The area code of an individual 8) The birth weights of female babies born at a large hospital over the course of a year 9) The length of the average hair on the heads of students in AP Statistics

1.2 Describing Distributions w/ numbers