Hypothesis

Prior to starting any lab activity, formulate a hypothesis. A hypothesis is a statement that explains the phenomenon that is being investigated (what would happen/because).

A hypothesis should be in the form of a statement, not an “if/then” prediction. Predictions should be reworked until it can be restated as a definitive statement. Grades are not determined by the accuracy of hypotheses, but if it is testable as written. It needs to be testable and falsifiable, and it must explain something about nature. In addition, a hypothesis involves experimentation, in-depth and comparative observation, as well as collection and analysis of various sources.

A hypothesis needs to have a because rationale. A hypothesis has explanatory power. Make sure you answer the why question with a because phrase.

Hypotheses can be formatted in the following manner: As the ________ (independent variable) changes (increases/decreases), the _____________ (dependent variable) will also change (increase/decrease) because ____________.

For example, individuals who go to college and obtain an education often earn higher incomes and enjoy a better lifestyle. This observation leads to the question: Does going to school and getting an education improve health and living conditions? Based on this question a hypothesis can be developed: Educated individuals live a better and healthy life because they receive a higher income and can make informed lifestyle decisions.

For another example, the following hypothesis could be developed based on our previous fermentation observation:
As the yeast concentration increases, more CO₂ will be produced because there is more yeast present to ferment.

Dependent Variable: In the fermentation lab, the amount of CO₂ produced is the dependent variable, what is being measured.
Dependent Variable: In the fermentation experiment, the amount of yeast is the dependent variable, what is being changed.
Treatment Group: Tubes 2-6 with increasing amounts of yeast. Sugar and temperature kept constant.
Controls: Tube 1 contains no yeast and is the negative control. Tubes 2-6 are the positive controls.

Variables in an Experiment:

Dependent Variable: Elements measured or counted by an investigator in response to a change in an experiment as a result of a change in the independent variable.
Independent Variable: A variable that drives/manipulates a change in the dependent variable. The investigator assumes that experimental outcomes can be predicted and even changed by changing/manipulating an independent variable.
Treatment Group: Section of the experiment in which an independent variable is manipulated.
Control Group: Section of the experiment in which an independent variable is omitted or set at standard value. This helps to evaluate how the manipulation of the independent variable affects the outcome of the experiment.

A hypothesis is not necessary for a laboratory exercise that only involves making observations of specimens or techniques. In other words, if there are no variables, then a hypothesis would not be required. For clarification, ask the laboratory instructor.