Prior to conducting the current study, Dr. Lonsbary asked her research assistant to use the same mood manipulation with a sample of 30 college students to determine if people’s moods really did change after listening to the music. Running this preliminary study helps establish validity.

Construct validity

Explanation:

In psychology, construct validity is a term that refers to the "degree to which a test measures what it claims to be measuring". In other words, it refers to the extent in which the instrument measures the construct in an adequate way.

Dr. Lonsbary is conducting a study about mood and music. (since the doctor wants to determine if people's moods change after listening to music). However, before conducting the study, her assistant is using the same mood manipulation method with a smaller sample to see if their moods really change when listening to music. In other words, they are trying to establish if what they are doing is actually measuring what it claims to be measuring (mood changes). Therefore, this study is helping establish construct validity.