A study where the researcher controls the variables by assigning subjects to groups is considered Hint, displayed below

The type of study where the researcher controls the variables by assigning subjects to groups is considered an Experimental Study.

Here are the steps that define this type of study:

1. Hypothesis: The researcher starts by forming a hypothesis about a certain phenomenon or behavior.

2. Selection of Participants: The researcher then selects a group of participants for the study. This group should be representative of the population the researcher wants to generalize the results to.

3. Assignment of Groups: The researcher assigns the participants to different groups. Typically, there is at least one experimental group (where the variable of interest is manipulated) and one control group (where the variable of interest is not manipulated).

4. Manipulation of Variables: The researcher manipulates one or more variables (independent variables) to see how this affects other variables (dependent variables).

5. Measurement: The researcher measures the dependent variables in both the experimental and control groups.

6. Analysis: The researcher analyzes the data to see if there are any differences between the groups. If there are, the researcher can conclude that the manipulated variable(s) caused the differences.

7. Conclusion: The researcher draws conclusions based on the results of the study. These conclusions can then be used to support or refute the original hypothesis.