We know when to expect to see strawberries at the store, or albacore at the offshore fishing grounds. Environmental changes that occur over time scales such as seasons and El Ninos can have dramatic effects on our coastal wildlife populations, and to really know if we are impacting our coastal ecosystems we need to understand this natural variability. There are only so many scientists out there. We can' t see as many areas or go out as often as we'd like to. The more information we have from as many places as possible, increases our power to see patterns caused by nature and by humans.
Variability is also important to know about when gathering and analyzing data.
Data has all kinds of variability, and this variability provides a treasure trove of information, some of which was already mentioned. However, the variability that we are interested in can be obscured by the variability that creeps in when we collect data, this is called error. As the amount of data-gathering error increases, our power to see REAL patterns in the data decreases. One way to keep data-gathering error at a minimum is to standardize our methods of data gathering as much as possible. The largest amount of error that we'll probably observe in the data that you are about to collect is the variability between people.