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handout_1_1 with nores

# handout_1_1 with nores - Chapter 1 Introduction statistics...

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Chapter 1 Introduction statistics - the science of learning from data data are numbers with a context- must know your field measurements from study are of little value without tools of statistics individuals - objects described by set of data (people, things…) variable - any characteristic of an individual Why? Why are we looking at this data? Who? Who are the individuals in the data set? What? What variables are in the data set? categorical variable - places an individual into one of several groups or categories EX- gender, race, ethnicity, hair color quantitative variable - takes numerical values for which arithmetic operations (adding, averaging…) make sense EX- height, distance, cost, time, income distribution - tells us what values a variable takes and how often it takes those values know what each variable is measuring often the rate at which something occurs is a more meaningful measure than a count EX- in 2002: 27,102 passenger cars were involved in fatal accidents 3339 motorcycles were involved in fatal accidents passenger cars had 21 fatal accidents per 100,000 vehicles motorcycles had 67 fatal accidents per 100,000 motorcyles

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1.1 Displaying Distributions with Graphs exploratory data analysis - examining data in order to describe their main features examine each variable by itself, then study the relationship between variables begin with graphs, then add numerical summaries Graphs for categorical variables distribution - lists categories and gives either the count or the percent Distribution of highest level of education for people aged 25-34 Education Count (millions) Percent Less than HS 4.6 11.8 HS 11.6 30.6 Some college 7.4 19.5 Associate degree 3.3 8.8 Bachelor’s degree
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handout_1_1 with nores - Chapter 1 Introduction statistics...

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