Growth Curves for a Mixture of Two Subpopulations

model

exponential

non-exponential

a

1

4.

t

c1

12.

m

1

6.

a

2

5.

t

c2

12.

m

2

1.

t

max

30.

y

max

10.

y(t) =

a

1

1-

-

m

1

t

c1



+

a

2

1-

-

m

2

t

c2



The growth curves of two-subpopulation mixtures can have shapes that are practically indistinguishable from those of a homogeneous population, but they can also have a variety of distinctly different shapes. This is shown with simulated growth curves generated with a double-stretched exponential model and a two-term non-exponential model. The Demonstration also shows how a minor change in one of the subpopulation's growth parameters can sometimes result in a major change in the shape of the mixture's growth curve.