Page 46 - Demo

6 Chapter 1 %u2022 Analyzing One-Variable Data Most data tables follow this format%u2014each row describes an individual and each column contains the values of a variable . Sometimes the individuals in a data set are called cases or observational units. DEFINITION Individual, Variable An individual is a person, animal, or thing described in a set of data. A variable is any attribute that can take different values for different individuals. For the ACS data set, the individuals are households. The variables recorded for each household are the region, number of people in the household, time in their current dwelling, whether the household has a smartphone, household income, and survey response mode. It is important to note that household is not a variable in this data set%u2014the numbers in that column of the data table are just labels for the individuals. Region, time in dwelling, smartphone status, and response mode are categorical variables. Number of people in household and household income (in dollars) are quantitative variables.DEFINITION Categorical variable, Quantitative variable A categorical variable takes values that are labels, which place each individual into a particular group, called a category. A quantitative variable takes number values that are quantities%u2014counts or measurements. Not every variable that takes number values is quantitative . Zip code is one example. Although zip codes are numbers, they are neither counts nor measurements of anything. They are simply labels for a regional location, making zip code a categorical variable. Time in dwelling from the ACS data set is also a categorical variable because the values are recorded as intervals of time, such as 5%u20139 years. If time in dwelling had been recorded to the nearest year for each household, this variable would be quantitative. In many data sets, the variable %u201cyear%u201d is treated as categorical. But it depends on how the data are being used. Consider a data set about cars, in which one of the variables recorded is model year. If we want to know what percentage of cars on the road are 2024 models, we treat year as categorical. If we want to know the average age of cars on the road, we would convert model year to age (in years) and treat this variable as quantitative. caution!So you want to be happy? Individuals and variables PROBLEM: The American Statistical Association sponsors a project called Census at School that collects data%u00a0about primary and secondary school students using an online survey. We selected a random sample of 40 U.S. high school students who completed the survey in a recent year. The table displays EXAMPLE kali9/Getty Images%u00a9 Bedford, Freeman & Worth Publishers. For review purposes only. Do not distribute.