Biologists observe the world around them. Our ability to observe has been greatly enhanced by technologies such as electron microscopes, rapid genome sequencing, magnetic resonance imaging, and global positioning satellites. These technologies allow us to observe everything from the distribution of molecules in the body to the movement of animals across continents and oceans.

Observation is a basic tool of biology, but as scientists we must be able to quantify the information, or data, we collect and observe. Whether we are testing a new drug or mapping the migrations of whales, it is essential to apply mathematical and statistical methods to the data we collect. In our opening discussion of the responses of corals to temperature, it was essential for Rachael to measure temperatures accurately and to have a physical measure of bleaching so she could compare the responses of her corals to different conditions and conclude that the differences were more than just random variation.