Experiment Design Terminology
- Experiment
- A planned, organized method to test a prediction, an inference or an explanation.
- Manipulative experiment
- When the experimenter actively changes (manipulates) the experiment variables. This is usually what people think of when you say "experiment".
- Observational experiment
- If the scale of the observations or ethical issues preclude the experimenter from making changes, then observations of different situations or reactions to natural changes are made.
- Manipulated variable
- The variable that the experimenter changes. Also called the independent variable.
- Levels of manipulated variable (treatments)
- The actual amounts or values the manipulated variable will take on. Also called levels of treatments or just 'treatments'.
- Responding variable
- The variable that the experimenter will measure. This variable responds to the variable the experimenter changes. Also called the dependent variable.
- Controlled variables
- The variables that the experimenter keeps constant during the experiment. Also called the constants.
- Hypothesis
- A possible answer to the question, an explanation.
- Experimental Control
- An experimental situation or special group of test subjects (the controls) that has nothing done to them. The controls will be used for comparison at the experiment's end.
- Quantitative measurements
- Data gathered that are referenced to a standard (usually numbers and units). Examples include age, distance, time, temperature.
- Qualitative measurements
- Data gathered about characteristics or qualities. Examples include color, taste, texture.