Some physical measurements are the average of the measurements of
microscopic quantities. 
Think of how the temperature of a bath is related to the energy of
the individual water molecules, for example. 
Suppose instead of the individual logistic maps
x^{i}_{t}, we see only
their average value z_{t} at each time step t, 
z_{t} = (x^{1}_{t} + ...
+ x^{N}_{t})/N 
We shall drive an IFS with the sequence of these averages 
z_{1}, z_{2}, z_{3}, ... 
Though there are many possibilities, we consider only a
simple example: 
two logistic maps, both with s = 4. 
Here the coupling formula becomes 
x^{1}_{t+1}  =  (1c)L(x^{1}_{t}) +
cL(x^{2}_{t}) 
x^{2}_{t+1}  =  (1c)L(x^{2}_{t}) +
cL(x^{1}_{t}) 

We shall use driven IFS and return maps to discover some coupling values
where these two chaotic logistic maps synchronize. 