A music teacher had noticed that some students went to pieces during exams. He wanted to test whether this performance anxiety was different for people playing different instruments. He took groups of guitarists, drummers and pianists (variable= Instru) and measured their anxiety (variable = Anxiety) during the exam. He also noted the grade of exam they were taking (in the UK, musical instrument exams are known as ‘grades' and range from 1 to 8). He wanted to see whether the type of instrument played affected performance anxiety when controlling for the grade of the exam. What analysis should he use?
Independent analysis of variance.
Analysis of covariance.
Repeated measures analysis of variance.
Mixed analysis of variance.