1. Experimental study is a study in which the researcher manipulates some of the variables and try to determine how the manipulation i­nfluences other variables.
2. In an observational study, researchers simply collect data based on what is seen and heard and infer based on the data collected.
3. In an observational study, one or more ­independent variables are controlled so as to obtain information about their ­influence on the dependent var­iable.

Which of the above statements are true?