Such a basic models should be based on simple rules, so way in which resulting behaviour emerges from system could be easily observable.
In other cases results are more obvious and easily observable, such as with the decreased ethanol production of yeast referred to below.
This is easily observable with a red laser pointer.
Its high declination means it is easily observable from the northern hemisphere, where historically most large telescopes have been situated.
One easily observable fact about these examples is that they prefer a unique intonation pattern.
They are often representative of other species in their habitat, being an easily observable and known species.
And it is also at odds with easily observable phenomena in contemporary China.
There really are mysterious phenomena that are easily observable and repeatable.
Although this region may be very thin, it can have significant and easily observable effects, such as causing a liquid to exhibit surface tension.
And the ideas that prompted them have an easily observable life cycle.