関連ワード:  what are variables in a data set    categorical variables in a data set    what are elements and variables in a data set    what are observations and variables in a data set    what is considered a variable in a data set    what is the independent variable in a data set    what is not a variable in a data set    what is the dependent variable in a data set    variables in a data set example    what are the variables involved in the structure of a data set