関連ワード:  what is a variable in a data set    what is a categorical variable in a data set    what is not a variable in a data set    what is the independent variable in a data set    what is the dependent variable in a data set    what is a variable in data collection    what is the number of times a variable appears in a data set    what are elements and variables in a data set    what are observations and variables in a data set    what is variable data