AP Statistics Chapter 2

The Five Ws *Who -are the cases *What -are the variables ( gives information about each of the cases) *Why -helps us to decide which way to treat the variable When - Where - *hoW- can make the difference between insight and nonsense

Classification of Variables Categorical variables- indentify a category for each case. ( usually think about counts of cases that fall into each category) or a variable that names categories can by with numerals or words Quantitative variables- record measurements or amounts of something. Must have units or a variable in which the numbers act as numerical values

Vocabulary Context- The context ideally tells Who was measured, What was measured, How the data were collected, and the when and the why the study was performed. Data -Systematically recorded information, whether number or labels, together with its context.

Vocabulary Continued Data Table- An arrangement of data in which each row represents a case and each column represents a variable. Case - is an individual about whom or which we have data. Population - all cases we wish we knew about Sample -the cases we actually examine in seeking to understand the much larger population

Vocabulary Continued Variable - hold the information about the same characteristic for many cases. Units- a quantity or amount adopted as a standard measurement, such as dollars, hours or grams

WHAT CAN GO WRONG? Dont label a variable as a categorical or quantitative without thinking about the question you want it to answer.( the same variable can take different roles) Just because your variables values are numbers, dont assume that its quantitative.(Look at the context) Always be Skeptical : context colors our interpretation, so those who want to influence what you think may slant the context.