tQx

In actuarial science, the symbol tqx is the notation for the probability of somebody dying anytime from the year denoted x and the t years following x. Typically it's given as a function, and typically it turns out that the area underneath the function between 0 and about 110 is 1, which implies that there is a 100% chance that you've died at age 110. So the function might be something like (t)Q(x) = (1/10) * e (-1/10)*x, where x is your age. You have to work with it a lot, and you use it to construct mortality tables, probabilities of dying, and from there you'd calculate how much premiums the group should pay based on their expected lifespan, etc., etc.

Typically the whole concept seems pretty distance, but sometimes our teacher Ron brings it back home. In class, he often gives examples of tQx for something like, "If you have an equal chance of dying every year before 100, and you're all 20 now, when will most of you be dead?" Sixty, of course. And some kids look around the room, like "Holy crap, we're actually dealing with dying people here." Recently he was doing an example, which requires some math to understand, but in case you're unfamiliar I'll explain a little bit. We were working with an operation, and the point is that if you input a number of about 115, the operation will tell you that everyone has died. The question in class was what number to put in to assure everyone had died, and someone responded "infinity." Technically, it's correct, but you don't need to go that high.

Our teacher responded, "Hmm, well, that's certainly safe." He has a way of making everything seem mundane even when it's not, in a good way - he smiles a lot and often stands akimbo and nods just a tad. "Yeah, well... I suppose no one's getting out of here alive," he finished.

Just in case you're interested, your chance of dying can be predicted almost exactly using a really simple equation, with a simple principle. The principle is that as you get older, you get worse and worse at warding off the effects of aging and mortality. The guess was that you get worse exponentially as time goes on. It requires math again, but to explain, the "force of mortality" for you at any moment is e^[.0004 + .00002x^1.103] or so. It seem like low numbers, I know, but if you add it up, it guarantees you're dead by about 111.

It's strange how with all the complexities of life and nature biology, we can figure it all out with five numbers.

Peace out.