Scientific Method Concepts

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Observation

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What is seen or measured.

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Inference

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A conclusion based on observation or evidence.

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Hypothesis

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An untested prediction. A good hypothesis states both cause and effect ("If-then" statement).

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Theory

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A broad explanation of natural events that is supported by strong evidence.

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Experimental Group

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Group being tested or receiving treatment (e.g., new drug).

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Control Group

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"Normal" group. Should be identical to the experimental group in every way except one. It does not receive the treatment (e.g., no drug, or given a placebo).

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Placebo

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A sugar pill or other "fake" treatment given to the control group so subjects do not know which group they are in.

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Independent Variable

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Variable that is being tested (e.g., new drug). In a graph, it is always plotted on the X axis.

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Dependent Variable

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Variable that is measured at the end of an experiment; the results (e.g., does the patient get better?). It is always plotted on the Y axis.

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Characteristics of a Good Experiment

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1. Can be repeated by anyone and get the same results. 2. Have a large sample size/many test subjects. 3. Are performed for longer periods of time.