# Statistics and Probability 13.1 Basic Statistics

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Statistics and Probability 13.1 Basic Statistics
Essential Question: Why is a knowledge of basic statistics helpful in real-world situations? Statistics and Probability 13.1 Basic Statistics

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

13.1 Basic Statistics Types of Data Example 1
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

13.1 Basic Statistics Data Displays Example 2/Example 3/Example 4
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

13.1 Basic Statistics Flavor Frequency Relative Frequency Vanilla 6
6/30 = 0.2 = 20% Chocolate 12 12/30 = 0.4 = 40% Butter pecan 4 4/30 ≈ 0.13 ≈ 13% Mint chocolate chip 8 8/30 ≈ 0.27 ≈27%

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%

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

13.1 Basic Statistics

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

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

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 4 5 6 3 4 7 7 8 9 10 3|2 = 32

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

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