Chapter 1: Introduction Statistics Day 1 Chapter 1: Introduction

Types of data! Categorical -- also called count data. Simply records which category a person or thing falls. Quantitative - (numerical) data – numerical values for which arithmetic operations make sense. You can find the arithmetic average of this data.

AP TEST CHECK!!

Categorical vs. quantitative variables Would the variable “monthly rainfall in Michigan” be considered a categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables (answer) Would the variable “monthly rainfall in Michigan” be considered a categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables If we asked people to report their “weight,” would that variable be considered a categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables (answer) If we asked people to report their “weight,” would that variable be considered a categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables We then asked people to classify their weight as underweight, normal, overweight, or obese. Would this variable now be categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables (answer) We then asked people to classify their weight as underweight, normal, overweight, or obese. Would this variable now be categorical or quantitative variable? categorical quantitative

Categorical vs. quantitative variables What type of data is produced by the answer choices for this question? categorical quantitative How many times have you accessed the Internet this week? None Once or twice Three or four times More than four times

Categorical vs. quantitative variables (answer) What type of data is produced by the answer choices for this question? categorical quantitative How many times have you accessed the Internet this week? None Once or twice Three or four times More than four times

Example Question 1 State Number of family Members Age Gender Marital Status Total Income Travel time To work Kentucky 2 61 Female Married 21000 20 Florida 6 27 21300 Wisconsin Male 30000 5 California 4 33 26000 10 Michigan 3 49 15100 25 Virginia 26 25000 15 Pennsylvania 44 43000 22 Never Married/single 3000 1 30 40000 New York 34 Separated 40

Distribution The distribution of a variable tells us what values the variable takes and how often it takes these variables.

Example 2 Example 2: Jake is a car buff who wants to find out more about the vehicles that students at his school drive. He gets permission to go to the student parking lot and record some data. Late he does some research about each model of car on the internet. Finally, Jakes makes a spread sheet that includes each car’s model, year, color, number of cylinders, gas mileage, weight, and whether it has a navigation system. Who are the individuals in Jake’s study?   What variables did Jake measure? Identify each as categorical or quantitative.

Statistical Inferences uses collected data to make generalizations about the entire group. Produces answers to specific questions and a statement of how confident we can be that the answer is correct. (NOTE: We cannot predict with absolute certainty! We cannot make predictions about individual cases!)

Activity 1 Hiring Discrimination

Assignment Page 7 1,2,3,7,8