Chapter 2 - What is Science? Scientific Inquiry The "Scientific Method" is a systematic approach to advancing knowledge. There are differences among scientists and among disciplines concerning the details of the method.  Many of the steps involved in a typical scientific investigation are discussed below.

The Scientific Method Observation Hypothesis Experiment Results Statistics Conclusion

Do Scientists Prove Hypotheses? When a hypothesis is disproven it is rejected and an alternative hypothesis is accepted. However, you cannot be 100% sure that the hypothesis is false. You may reject a hypothesis that is true. Statistical techniques are used to reduce this type of error.

Theory Hypotheses that have been tested by different investigators numerous times and have not been disproved become theory.

Experimental Design Scientists often perform experiments by doing some sort of a manipulation. In the example in your notes one group of mice was given a hormone and the other group was not. The group of mice that was not given the hormone is referred to as a control. A control serves for comparison. If the average weight of the control mice had been the same as that of the group given the hormone, it would be necessary to conclude that the hormone did not cause a change in growth.

Variables

Variables cont’d Heart rate and speed are both referred to as variables. Heart rate depends on speed, so it is called a dependent variable. Speed does not depend on heart rate; it is an independent variable. Dependent variables are always plotted on the Y-axis (vertical axis). Independent variables are plotted on the X-axis (horizontal axis).