stat 2000 test review

stat 2000 test review - Variables Categorical Qualitative...

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Variables • Categorical / Qualitative – Classifies subject by an attribute or characteristic. – Hair color, type of professor, make of car • Quantitative – Gives numerical measures of subjects. – Weight, height, response time, number of miles traveled to work Quantitative Variables • Discrete – A countable number of whole-numbered values (no decimals). • # of people entering a shop per hour (whole number) • # of living grandparents (0,1,2,3,4 only) • # of spades in a poker hand (0,1,2,3,4,5 only) • # of balls a juggler is currently juggling • Continuous – Can take on any numerical value (including decimals) on an interval. • Weight of an athlete (150, 150.01, 181.312, etc) • Time taken to complete a lap • The current speed of an airplane Examples (HW 1.1-2.1) Which of these are categorical or quantitative? For the latter, which are discrete or continuous? Length of an earthworm (in mm) Region of U.S. (Southeast, West, etc.) Literary genre Number of times in one month the Creswell fire alarm goes off Important Terms • Population – Total set of subjects in which we are interested • Sample – A subset of the population for which we have data • Subject – Entities we measure (individuals) Important Terms • Parameter – A numerical value summarizing the population data. – Ex: number of freshmen out of all STAT 2000 students • Statistic – A numerical value summarizing the sample data. – Ex: number of freshmen out of a sample of 100 STAT 2000 students • Statistic and Sample both begin with S Example (HW 1.1 – 2.1) • A college dean wants to know the average age of the faculty. She takes a random sample of 10 faculty members and averages their ages. Population = Sample = Subject = Parameter = Statistic =
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Descriptive vs. Inferential • Descriptive Statistic – Summary of the data in the sample. • Majority of students in a sample of 1000 attend UGA football games • Inferential Statistic – A conclusion or prediction about the population based on the sample data. • Majority of all UGA students attend UGA football games, based on the sample Frequencies Example: 18 cookies out of a random sample of 32 are chocolate chip proportion = frequency total number of observations percentage = frequency total number of observations ! " # $ % 100 proportion = 18 32 = .5625 percentage = 18 32 ! " # $ % 100 = 56.25% Frequencies (HW 2.1-2.2) • Results from the question of how many children a family has had. Fill in the answers. • # Children 0 1 2 3 • Count 786 460 662 489 Proportion Percentage Types of Charts (Categorical) Bar Graph Categories on horizontal axis, frequency on vertical axis, height of rectangle is frequency Pareto Graph A bar graph arranged with bars in descending order of frequency Types of Charts (Categorical) Pie Chart A circle divided into slices, with each slice representing a category
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stat 2000 test review - Variables Categorical Qualitative...

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