True Score

A true score is the actual amount of something that a person is attempting to measure. Consider measuring how fast an object is moving. One might say, “My car is moving at 55 miles-per-hour,” but 55 miles-per-hour is a relative assessment to some stationary position. Moreover, the Earth moves around the Sun, but the reported speed of the car does not consider the movement of the Earth around the Sun. Furthermore, Earth rotates on an axis; thus, any statement about how fast a car is moving does not consider the movement that is part of the rotational speed of the Earth on an axis. The introduction of relativity means that the idea of measuring the speed of a car is really a relative evaluation. Finally, consider a NASCAR race, like that at Talledega where the cars often exceed 200 miles-per-hour. At the end of the race, the cars are back where they started; the race is in a circle and the winner ends up where he or she began.

The social sciences can be more problematic. What is the absolute level of communication skills, humor, or leadership? The idea of a true score existing for something like leadership may be a myth. A true score requires an anchor point to provide a means of measurement in a very strict sense. Of course, when measuring, a researcher obtains a score, sometimes referred to as the “obtained” or “observed” score. The score is the best estimate of what the researcher believes the true score value should be. This entry introduces the idea of true scores, paying specific attention to the difference between measured and true scores and the impact of random errors on true scores.