The most common and obvious fossils are the preserved skeletal remains of animals. Other fossils, which are also evidence of past organisms, include leaf impressions, tracks and trails, burrows, droppings, and root casts.
Lesson Summary. Non-experimental research does not mean nonscientific. Non-experimental research means there is a predictor variable or group of subjects that cannot be manipulated by the experimenter. Typically, this means that other routes must be used to draw conclusions, such as correlation, survey or case study.
The third type of experiment is the observational experiment, which is used when there is no way to control variables. These types of experiments happen outside of the laboratory and may be called a non-experimental method. Just like the quasi-experimental type of method, there is a great deal of effort made to identify all variables that may be influential on the variable of interest.