関連ワード:  what is a control variable in a study    what is a independent variable in a study    what is a control variable in a research study    what is a control variable in a research    what is a independent variable in a research study    what is the purpose of using a control variable in a study    what is the role of a control variable in a research study    what is a control variable in quantitative research    what is a independent variable in research    what is the independent variable in a correlational study  
結果 : what is a control variable in a study