1 Introduction to Statistics

2 What Is Statistics? Statistics is the science of collecting, organizing, and interpreting numerical facts, which we call data Examples of data: 1. High and low temperatures for this week in SF: San Francisco Weather Forecasts on Yahoo! Weather San Francisco Weather Forecasts on Yahoo! Weather 2. The number of imported car sales and that of domestic car sales in this year

3 The Goal of Statistics The goal of statistics is to gain understanding from data and then make decision using the gain. 1. So you know what to wear. 2. So the government can justify their tax policy for importing car.

4 The Rise of Statistics The ideas and methods of statistics developed gradually as society grew interested in collecting and using data for a variety of applications. 1. The earliest origin is the desire of rulers to measure the value of taxable land in their domains. 2. Starting at 17 th century, the importance of careful measurements of weights, distances, and other physical quantities grew. 3. By the 19 th century, the agricultural and life sciences began to reply on data to answer fundamental questions.

5 Who Use Statistics?

6 Media Television News – KTVU Channel 2 KTVU Channel 2 News Papers – USA Today USA Today Polls – Gallup Poll Gallup Poll Web/TV Commercials

7 Government U.S. Department of Labor – Bureau of Labor StatisticsBureau of Labor Statistics U.S. Census Bureau Department of Health &Human Services Others

8 Other Organizations American Heart Association American Lung Association American Cancer Society California Lottery

9 Case Studies Summary statistics vs. raw data Change in the rate; include baseline rate Representative sample Unrepresentative sample Observational study Randomized (control) experiment Statistical significance doesn’t imply practical importance

10 Who Are Those Speedy Drivers? What question would you ask? **Q: What’s the fastest you have ever driven a car?___ mph. ** Ask 5 students of each gender for their answers and write them on the board and show medians. (summary stat vs. raw data) ** Q: Is this a representative sample of the whole class? (representative vs. unrepresentative samples)

11 Who Are Those Speedy Drivers? In CSUEB. How would you get a proper dataset for this problem? ** Is your study an observational study or randomized study? ** Can our finding be applied to the whole population (CSUEB people)? ** If on average, male drivers are 4 mph speedier than female drivers, would male drivers get more speedy tickets than females? (Stat vs. practical significance)

12 Should We Drop The Course? The “F” grade rate is doubled for the instructor compared to other instructors. ** Baseline rate: 1 in 50  2 in 50 ** Baseline rate: 5 in 50  10 in 50 (Change of rate study must include baseline rate to see if it is practically significant.)

13 Reading Assignment Chapter 1 of textbook Find a case study online and discuss the study