Sun mi is designing a questionnaire on loneliness. she is concerned that some features of loneliness are similar to depression and to low self-esteem. what type of validity does she need to show to demonstrate that her questionnaire assesses loneliness and not depression or low self-esteem?

The type of validity that she needs to show to demonstrate that her questionnaire assesses loneliness and not depression or even low self-esteem is that she should have a Discriminant validity. A discriminant validity is the one responsible for testing measurements that are not related in some way in which this will differentiate loneliness and depression that would make her study to be more discernible.