Logistics ...

Okay, so we've done linear, and we've done exponential. But there are a lot more functions to consider.

For instance, sometimes things start off growing really fast like an exponential function, but then things happen to slow down the growth. We talked in class about how the flu spreads exponentially, but then slows down and levels off when people start taking medicine. This is called a LOGISTIC function.

Here's what it looks like in action (re-creation of the game we played in class, in case you missed it) - each turn, each person that is already sick picks a random person to get them sick. But when the numbers start repeating themselves, people can't get sick AGAIN, so the growth slows down.

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 a little while later ...

We can do a regression on this type of function, just like with linear or exponential. The calculator steps are:

(1) Put data in, with [STAT] EDIT
(2) [STAT] CALC "B" (LOGISTIC)
(3) Turn on the StatPlot ([2nd] [Y=]), set the [WINDOW], and type the regression into [Y=]
(4) Graph