Answer:
The research method used in this study is Non-experimental method.
Explanation:
The Non-experimental research method occurs when the researcher can not manipulate or control the subjects or independent variable involved in a situation, and therefore have to rely on their observations and interpretation to make a conclusion, such as in the example given: Dr. Sears draws a conclusion of a situation and participants he can not manipulate (the individuals in a department store) based on observations made.