Scientific Method Vocabulary Review Compiled By Robert Strawn

Stating the problem What do you want to know? What causes leaves to change color during the fall? State the problem as a question. Example: Why do leaves change colors in the fall ?

Hypothesis An hypothesis is a limited statement regarding cause and effect in specific situations; it also refers to our state of knowledge before experimental work has been performed and perhaps even before new phenomena have been predicted. A hypothesis is a tentative explanation about the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena.

Experiment Scientist use an experiment to look for cause and effect relationships in nature. They design an experiment so that changes to one Variable (any factor, trait or condition that exist in differing amounts or types), causes something else (another variable) to vary in a predictable way. Experiments test hypothesis.

Independent variable Sometimes called the manipulated variable. The part of the experiment that is manipulated or changed by scientists or persons performing the experiment. Independent Variable = what you are testing or what you are in control of or what you manipulate

Dependent Variable Some times called the responding variable The part of the experiment that is being affected by the independent variable. Changes in the Dependent variable are caused by a change in the independent variable. Dependent Variable=what you are measuring

Controls or Controlled Variables Quantities that a scientist wants to remain constant. A part of the experiment that is not being tested and is used for comparison of the experimental results. A control group should be used when conducting an experiment. This group receives the same attention as the test groups, however, it will not be influenced by the variable the other groups are testing.

Constants Controlled variables are quantities that a scientist wants to remain constant, and he must observe them as carefully as the dependent variables.

Other Important Terms Sample: a chosen population to represent a scientific study. - Example: AHS students, Males, Hispanics, - Use common sense when choosing a sample -Random sampling- Each member of the population has an equal chance of being selected. (best sample) Experimental group: group(s) subjected to the independent variable Control group: group not subjected to the independent variable, used as measuring stick

Reproducibility reproducibility: producing the same result consistently to verify result. It is therefore important to describe your experimental design in enough detail for others to perform the same experiment. A successful Experiment is repeatable. –By anyone. –Examples: –Cold Fusion (1989) –Ecstasy (Science, 2003)

Assumptions Assumptions: factors thought to be true for the investigation but have not been verified or controlled –Commonly accepted information –Thought to be held constant but not controlled –Factors beyond the investigators control because of technical or time considerations Incorrect assumptions invalidate an experiment!

Statistics Statistics – using mathematics to organize, summarize, and interpret numerical data Mean: arithmetic average of scores Variability = how much scores vary from each other and from the mean