Three key types of experiments are controlled experiments, field experiments, and natural experiments.

In an experiment, an independent variable (the cause) is manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled. An advantage is that experiments should be objective. The views and opinions of the researcher should not affect the results of a study.

The researcher has no control over the variables in an observational study. An experiment is a method of applying treatments to a group and recording the effects. Remember, a good group experiment will have two basic elements: a control and a treatment.

A designed experiment is a series of runs, or tests, in which you purposefully make changes to input variables at the same time and observe the responses. In industry, designed experiments can be used to systematically investigate the process or product variables that affect product quality.

DOE is a powerful data collection and analysis tool that can be used in a variety of experimental situations. It allows for multiple input factors to be manipulated, determining their effect on a desired output (response).

Terms in this set (6)

1. Identify the problem or question.
2. Form a hypothesis or solution to the problem.
3. Design the experiment to be used to test your hypothesis.
4. Carry out experiment.
5. Analyze data and observations.
6. State conclusion.

A type of experimental design where the researcher randomly assigns test units and treatments to the experimental groups. Examples of true experimental designs are: pre-test – post-test control group, post-test only control group, and a Solomon four group, six-study design.

Experimental design means creating a set of procedures to test a hypothesis. A good experimental design requires a strong understanding of the system you are studying. By first considering the variables and how they are related (Step 1), you can make predictions that are specific and testable (Step 2).

Example of a True Experiment Sarah’s hypothesis is that Drug X causes a decrease in anxiety. Sarah’s independent, or predictor, variable is Drug X. Her dependent, or outcome, variable is anxiety. Sarah will manipulate the dose of Drug X to see if it causes a decrease in anxiety.

A true experiment is defined as an experiment conducted where an effort is made to impose control over all other variables except the one under study. Independent variable – this is the variable that the experimenter manipulates in a study.

An experiment may include multiple experimental groups at one time. A control group is a group separated from the rest of the experiment such that the independent variable being tested cannot influence the results. While all experiments have an experimental group, not all experiments require a control group.

While there are several important considerations that go into creating a good experiment, the essential parts are the treatment and the control. The experimental treatment is the thing that you are testing.

In a scientific study, a control group is used to establish a cause-and-effect relationship by isolating the effect of an independent variable. Researchers change the independent variable in the treatment group and keep it constant in the control group. Then they compare the results of these groups.