Selecting variables to study You have selected the following prediction to test: Previously thinned forests will have higher tree survival than adjacent forests that were not thinned. Now you need to define the key variables that you will use to test this prediction. For the following variables, sort them as independent variables, dependent variables, or variables that should be controlled (held constant). See the hints for more information about variables. View Available Hint(s) Reset Help thinning or no thinning before the fire elevation of the site dominant tree species tree survival rate after the fire Independent variable | | Dependent variable Controlled variable thinning or no thinning before the fire elevation of the sitedominant tree species tree survival rate after the fire Independent variable Dependent variable Controlled variable

Independent variables are those variables which is changed or controlled in an experiment;here in this case thinning of forests(variable) will be changed or we can say will be different before the fire(fire is the condition for the variable to change)

Dependent variable:tree survival rate after the fire

Dependent variables are those variables which need to be tested and measured in an experiment;here in this case survival rate needs to calculated which will be calculated after the fire(how many trees survived after the fire)

Controlled variable:elevation of the site,dominant tree species

Controlled variables are those variables which are kept constant and unchanged throughout the experiment;here in this case the site of prediction and species of trees which are dominant remained constant