Conducting Your Own Research Project

Posing A Question

One thing to keep in mind is that our purpose here is to demonstrate to you (show you) how to conduct an "objective" study. We're not looking at "opinion polls" or what people think. As co-investigator John Yandell pointed out a lot of very experienced professions in tennis felt that the ball speeds up after it bounces on the court. That isn't true though. Those opinions even though they are from experienced players are "subjective". We're also not talking about looking for "records". For example, what's the fastest serve speed ever recorded? So what we're demonstrating here is how to conduct an "objective" study - a study that is not influenced by emotions or personal feelings; a study that is based on an observable experiment.

Another concept that you'll hear us talk about is whether we can obtain a "quantitative" or "qualitative" result. What does that mean exactly? Quantitative sounds like the word "quantity". When we talk about "quantitative results" we mean that we can represent the result with a number. For example, John quantified the amount of spin on the ball for different players; Nasif quantified the velocity of the ball speed for different players and came up with a number; Jani and the engineers at CAI came up with the angle the ball makes with the court before and after the bounce - the spin rate, the velocity and the angles are all numbers.

Qualitative Versus Quantitative

So what does qualitative mean? It means that there's some distinguishing characteristic that can be observed. For example, during our wind tunnel test we did not use any special instruments to calculate the forces (a number) on the tennis ball. We used smoke in the tunnel so that we could observe the changes as we ran through our different experiments. Much like reading an X-ray, the smoke patterns mean something to an aerodynamicist, and we can see that lift and drag were being created even though we do not assign a number value to the results.