Chapter 2: Data by Alyssa Webb

● Data can come in many different types but it useless without it’s context. ● Not all data represented by numbers is numerical. (ex: 1=boy, 2=girl) ● Who, What, When, Where, Why, and How? provides context for data. ● If you can’t answer Who and What, then you don’t have data. What are Data?

● Who are the cases for which we have collected data. ● Respondents- people who answer a survey ● Subjects/ Participants- people whom we experiment ● Experimental Units- animals, plants, and inanimate objects Who

● The characteristics recorded about each individual are called variables. They should have a name that identifies What has been measured. ● The Why of analysis will shape how we view the variable. What and Why

● categorical- when a variable names categories and answers how cases fall into these categories ● quantitative-when a measured variable with units answers questions about the quantity Variable Types

● Where and When give us information about the context. ● How the data are collected can make the difference between insight and nonsense. Where, When, and How

● Identifier variables- categorical variables with exactly one variable in each category. ex: Social Security number, FedEx tracking number, ect. Identifying Identifiers

● A data table is an arrangement of data in which each row represents a case and each column represents a variable. ● A case is an individual about whom or which we have the data. ● A variable hold information about the same characteristics for many cases. Data Tables

For each description of data, identify the W’s name, the variables, specify for each variable whether its use indicates it should be treated as categorical or quantitative, and, for any quantitative variable, identify the units in which it was measured (or note that they were not provided). Homework Problems

In the Spring 2001 issue of Chance magazine, a psychology professor reported on data he had collected about his sleep patterns. He kept daily records of the number of hours of sleep he got, whether or not he suffered from “early awakening”, whether or not he watched TV in the morning and in the evening, the number of hours he spent standing during the day, and his mood (happy/sad, on a scale from 10-90). problem #23

Who- Days What- Sleep, wake early, TV, hours standing, mood When Where- At home Why- To analyze sleep patterns How- Daily recording Variable- Sleep, quantitative, hours Variable- Wake early, categorical Variable- Tv, categorical Variable- Hours standing, quantitative, hours Variable- Mood, quantitative, scale problem #23 answer

The Kentucky Derby is a horse race that has been run every year since 1875 at Churchill Downs, Louisville, Kentucky. The race started as a 1.5 mile race, but in 1896 it was shortened to 1.25 miles because experts felt that 3-year -old horses shouldn’t run such a long race that early in the season (it has been run in May every year but one when it took place on April 29). Here are the data for the first few recent races. problem #25

Who- Kentucky Derby Races What- Date, winner, margin, jockey, net proceed to winner, duration, track condition When to 2004 Where - Churchill Downs, Louisville, Kentucky Why- To see horse race trends How- Official statistics collected at the races Variable- Year, quantitative, day and year Variable- Winner, identifier Variable- Margin, quantitative, horse lengths Variable- Jockey, categorical Variable- Net proceeds to winner, quantitative, dollars Variable- Duration, quantitative, minutes and seconds Variable- Track condition, categorical problem #25 answer