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Chapter 1 - Introduction Math 22 Introductory Statistics
What is Statistics? • Statistics - Involves the collection, organization, interpretation, and presentation of numerical information.
Introductory Terms • Experimental Units - Subjects • Variable – A characteristic of interest about each individual element of a population or sample • Observations – Particular information that we collect from each subject. • Data Set – Collection of observations.
Items That We Might Want to Study • Population - Collection of all objects or items that are of interest in a statistical study. • Sample - A finite portion (subset) of the population that is used to study the characteristics of concern in the population. • Target Population - Population of interest in the study.
Items That We Might Want to Study • Parameter – A numerical value summarizing the entire population • Sample Statistic – A numerical value summarizing the sample data. • Census - A sample consisting of the entire population. (An attempt to sample the entire population)
Descriptive and Inferential Statistics • Descriptive Statistics - Describes the state of the data which has been collected. • Inferential Statistics - Generalizations or conclusions that extend beyond the collected data, what we call the population.
Levels of Measurement • Nominal Scale Variables that categorize without any form of natural ordering. • Ordinal Scale Variables that categorize with a form of natural ordering • Interval Scale Require a physical unit of measure. There is no absolute zero (starting point).
Levels of Measurement • Ratio Scale Very similar to interval scale variables. The key difference is that ratio scale variables have an absolute starting point, an absolute zero.
Types of Measurements • Numerical Variable (quantitative variable) - A variable whose values are numbers obtained by a measurement. • Discrete Variable • Continuous Variable
Types of Measurements • Categorical Variable (Qualitative Variable) - Variable whose values are classifications or categories. (i.e. Coding)