I’ve been thinking recently about how one ever demonstrates that nothing happened because something did happen. Specifically, with regard to the protests over police shootings, police abuse, etc., how does one demonstrate that new policies make a difference? The difference is noticed only when nothing happens. Undoubtedly, most police officer shootings happen because the officer had no choice other than to prevent being killed himself/herself, or to prevent someone else from being killed/injured. In other words, they are “good” shoots. But, with regard to the “bad” police shootings/arrests/killings, the only way to know if, for example, new policies on use of force are effective is if none of these things happen. Or, fewer happen. The positive result then, is when nothing happens. And, nothing, that is, the absence of something, must be tracked and measured. The same is true, sometimes, of our work as trial consultants. Many times, we evaluate the “what could happen.” There are times when there may be benefits to our clients of other things not happening (for example, with regard to the admission of certain evidence or of a witness’ performance – good or bad, etc.). Recently, a client mentioned something along these lines to Melissa as it pertains to jury selection, when she makes her recommendations to our clients based on what was said, and as this client pointed out, what was not said, by the prospective jurors. My mind follows strange paths sometimes, so, in thinking of these concepts, I thought of musical “ghost notes” (about which I learned vicariously from Melissa’s study of bass guitar). Per Wikipedia, “a ghost note is a musical note with a rhythmic value, but no discernible pitch when played.” In other words, it is a note that doesn’t happen (or isn’t audible), but it seems like it does. Using that analogy, ghost notes exist when things don’t happen as in the examples I gave. But, without them, something will be perceived as missing. Thus, it is important to recognize, or notice, what doesn’t happen as a result of a positive change being made.
David’s reference to ghost notes is quite impressive! Ghost notes are important to me, as a bass player. They are place holders, serving to keep the rhythm while not making a discernable musical sound. On the thick strings of a bass guitar, ghost notes sound like a mini cymbal, leading the way to the playing of the next note. They are fun to play! David’s musical reference aside, in the scientific world where I spend most of my time, predictions are made about what will happen, as opposed to what will not happen. How many times have I heard the expression, “The null hypothesis cannot be proven”? For readers without a science background, the null hypothesis is defined as the hypothesis to be accepted or rejected in favor of the alternative, research, hypothesis. Scientists devise experiments to test cause and effect, for example, “If I change the independent variable, X, what is the effect on the dependent variable, Y?”. If X is determined not to have an effect on Y, then the research hypothesis is rejected in favor of the null hypothesis, which is the absence of a causal relationship between X and Y. Applied to David’s example regarding police departments, a scientist hired to assist them in reducing the number of unjustified shootings might hypothesize that, if police officers receive training on differentiating between situations to determine if deadly force is justified, the number of unjustified shootings will decrease. One could then compare shootings by officers who had training with those who did not receive the training. However, in order to determine, with certainty, whether the training was effective, one would have to randomly assign some police officers to receive training and others, to receive no training. It is unlikely this will happen because most police departments would be unwilling to provide training to some, but not all, officers. Thus, David’s post leaves us with a conundrum about how positive changes can be made absent rigorous scientific study that would allow rejection of the null hypothesis. People who advocate social change, including in law enforcement, are well advised to obtain advice from scientists about the best ways to approach it. I will be glad to help, but first, I will play some ghost notes on my bass guitar!