# lec02 - STATISTICS 13 Lecture 2 What is Statistics As a...

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STATISTICS 13 Lecture 2 Sept 27, 2010

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What is Statistics? As a colloquial term : numerical facts – Sports statistics (e.g. basketball scores, goals scored in a season) – Business statistics (e.g. gross domestic product, total volume of transactions) As a discipline: the science that deals with the collection, classification, analysis, and interpretation of numerical facts or data : – What are the effects of a new drug? – Why parents and children show resemblance? – Why does casino make a profit at roulette?
What is Statistics? (Cont.) A statistical study involves: - Gathering data – Analyzing data – Making decisions under uncertainty

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Example: Population of US Population statistics of US -Collect data: by US census Bureau -A nalyze data: what is the trend of population size in US? -Make predictions: what would be the population size of US in 2020?
Example (cont.) “Linear trend” from 1980 to 2009: displaying data in a graph helps us to understand it US Population

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Variables A variable is a characteristic which varies from subject to subject or changes over time Examples: - Population size of US (changes over time) – Hair color (varies from person to person) – Blood pressure (varies over time and from person to person ) – Car mileage (varies over time and from car to car) – Annual rainfall amount of CA (varies over year)
Types of Variables Variables Qualitative Quantitative Discrete Continuous

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Types of Variables (cont.) Qualitative variables measure a quality or a characteristic of a subject Examples : – Eye color (black, brown, blue, hazel,…) – Gender (Male, Female) – Make of car (GM, Ford, Volvo,…) – State of birth (California, Pennsylvania, Alaska,…)
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lec02 - STATISTICS 13 Lecture 2 What is Statistics As a...

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