A researcher studying the topic of employee morale at a specific workplace uses the number of complaints filed by employees against their bosses as a measure of employee morale, and finds that the more complaints filed by employees the lower the workplace morale. Another researcher does a similar study at a different workplace and also finds that the higher the number of complaints filed by employees the lower the workplace morale. The number of complaints filed by employees against their bosses is best described as what kind of measure of workplace morale