Observing Earth through a Scientific Lens - Geology - page 15

I choose those 100 dogs wisely, they may be a very accurate representation of the world-
wide dog population. The best sample size is different for each experiment; it all de-
pends on the question being asked.
In earth science, experiments are often natural or observational. This means
that scientists go out into the field and observe events that have already
happened, such as the formation of rocks, rock layers, or features of the land-
scape. Scientists make these observations without changing any aspect of the
event or its result.
Geologists also use another kind of experiment called a manipulative experiment. A ma-
nipulative experiment is done in a laboratory, where the scientist can manipulate or
change certain factors in order to test which factors are most important in creating the
observed outcome. In this case, multiple experiments can be done, each one testing the
importance of a different factor (or variable), with the goal of zeroing in on the one (or
ones) that explain the observed outcome.
Most importantly, a scientific experiment, whether it is a natural or manipu-
lated experiment, must be repeatable. This means that the scientists must clearly
describe the steps they have taken so that another scientist can repeat the same
experiment and see if she too, gets the same result.
Crunching the numbers
After running experiments and making observations, a scientist is left with a large collec-
tion of information, or data, to use to draw a conclusion. Trying to find patterns in page
after page of descriptive observations or lists of numbers is almost impossible. To find
patterns in the data, a scientist uses statistics.
Statistics are a mathematical tool for describing and comparing information
(observations) quantitatively, which simply means using numbers. By using num-
bers to describe the data, such as the number of times a certain characteristic is