Statistics and Probability 13.1 Basic Statistics

1. Essential Question: Why is a knowledge of basic statistics helpful in real-world situations? Statistics and Probability13.1 Basic Statistics

2. 13-1: Basic Statistics • Population: The set of all people who can be chosen • Sample: The set of people from the population who were actually chosen • Example: Identify the population and the sample • There are three schedule options for classes at a high school: 90-minute classes every other day for a year, 90-minute classes every day for a semester or 45-minute classes every day for a year. Out of 1200 students, 50 students from each grade level are chosen at random and asked their preference. • Population: • Sample: 1200 students 50 students • 4 grades = 200 students

3. 13.1 Basic Statistics • Types of Data • Qualitative – categorical • Quantitative – numerical • Discrete – incremental • Continuous – no minimum difference • Example 1 • The height of each player on a basketball team • The style of shoes worn by each student in a class • The number of people in each household in the US Quantitative - continuous Qualitative Quantitative - discrete

4. 13.1 Basic Statistics • Data Displays • Frequency – number of times a value appears • Relative frequency – frequency/total number of items • Example 2/Example 3/Example 4 • 30 people were asked their favorite flavor of ice cream: 6 vanilla, 12 chocolate, 4 butter pecan, 8 mint chocolate chip. • Display as a frequency table, bar graph, and pie chart

5. 13.1 Basic Statistics

6. 13.1 Basic Statistics • Pie Chart • Each relative frequency takes a portion of 360˚ • Vanilla: 0.2 ∙ 360˚ = 72˚ • Chocolate: 0.4 ∙ 360˚ = 144˚ • Butter pecan : 0.13 ∙ 360˚ ≈ 47˚ • Mint chocolate chip: 0.27 ∙ 360˚ ≈ 97˚ Vanilla 20% Mint Chocolate Chip 27% Butter Pecan 13% Chocolate 40%

7. 13.1 Basic Statistics • Displaying Quantitative Data • Curve types • Uniform – all values have approximately same frequency • Symmetric – right and left sides are mirror images • Skewed right – right side lower than the left side • Skewed left – left side lower than the right side • Skewed means “screwed” • Outlier – data far removed from the rest. • Usually the culprit in skewed data

8. 13.1 Basic Statistics

9. 13.1 Basic Statistics • Example 5 - The shape of data • Choose the best determination of data (uniform, symmetric, skewed right, skewed left) • The last digit of each number in the phone book • The salaries of the employees of a corporation • The age of retirement for all people in the US • The height of all adult women in the US Uniform Skewed right Skewed left Symmetric

10. 13.1 Basic Statistics • Stem Plot • Choose leading digit(s) as stems • Arrange stems vertically • Last digit is the leaf • Provide a key

11. 13.1 Basic Statistics • 31 test scores on an exam • 32, 67, 89, 90, 87, 72, 75, 88, 95, 83, 97, 72, 85, 93, 79, 63, 70, 87, 74, 86, 98, 100, 97, 85, 77, 88, 92, 94, 81, 76, 64 3|2 = 32

12. 13.1: Basic Statistics • Assignment • Page 851 • Problems: • 1 – 9 (all) • 11, 15 • 19 – 24 (all)