# Math Insight

### Applet: Fitting a linear model to population change as a function of population size

In the table of the right panel, enter up to six values for the population size $P_t$ at time $t$. (In the right panel, $P_t$ is displayed as P_t.) The applet will automatically calculate the changes $P_{t+1}-P_t$ and plot the points $(P_t,P_{t+1}-P_t)$, which show the population change versus the population size at the beginning of the interval. By moving the points $A$ and $B$ (represented by the red diamonds) with the mouse, you can try to fit a line through the points and read off its slope. You can zoom in and out with the buttons label by + and -. The arrows allow you finer control over the zoom in each direction.

Applet file: population_change_versus_population_line.ggb