A complex measure is a way of measuring something that is involved and hard to understand because it has many parts. For example, a complex measure might be used to measure how well a student does in school. This measure might include things like the student's test scores, how many hours they study, how well they behave in class, and even things like their attendance and participation in extra-curricular activities. All these pieces are then combined to get a comprehensive view of how well the student is doing in school.