A quantitative evaluator, a qualitative evaluator, and a normal person are waiting for a bus. The normal person suddenly shouts, “Watch out, the bus is out of control and heading right for us! We will surely be killed!” Without looking up from his newspaper, the quantitative evaluator calmly responds, “That is an awfully strong causal claim you are making. There is anecdotal evidence to suggest that buses can kill people, but the research does not bear this out. People ride buses all the time and they are rarely killed by them. The correlation between riding buses and being killed by them is very nearly zero. I defy you to produce any credible evidence that buses pose a significant danger. It would really be an extraordinary thing if we were killed by a bus. I wouldn’t worry.”
Dismayed, the normal person starts gesticulating and shouting, “But there is a bus! A particular bus! That bus! And it is heading directly toward some particular people! Us! And I am quite certain that it will hit us, and if it hits us it will undoubtedly kill us!”
At this point the qualitative evaluator, who was observing this exchange from a safe distance, interjects, “What exactly do you mean by bus? After all, we all construct our own understanding of that very fluid concept. For some, the bus is a mere machine, for others it is what connects them to their work, their school, the ones they love. I mean, have you ever sat down and really considered the bus-ness of it all? It is quite immense, I assure you. I hope I am not being too forward, but may I be a critical friend for just a moment? I don’t think you’ve really thought this whole bus thing out. It would be a pity to go about pushing the sort of simple linear logic that connects something as conceptually complex as a bus to an outcome as one dimensional as death.”
Very dismayed, the normal person runs away screaming, the bus collides with the quantitative and qualitative evaluators, and it kills both instantly.
Very, very dismayed, the normal person begins pleading with a bystander, “I told them the bus would kill them. The bus did kill them. I feel awful.”
To which the bystander replies, “Tut tut, my good man. I am a statistician and I can tell you for a fact that with a sample size of 2 and no proper control group, how could we possibly conclude that it was the bus that did them in?”