Pete Avitabile shares his views on different aspects of the concept of modal space. He states that for performing modal test one needs to check different measurement locations and in different directions. This is critical especially if one really does not know what all of the modes of the system might be. It does not make any sense to select all the points until one has some idea hat all the modes might be for the system. One can select many more measurements, but with the understanding of what the shapes might be after knowing what all the mode shapes might be.