What is an example of a positive control?

As a positive control, you might swab an existing colony of bacteria and wipe it on the growth plate. In this case, you would expect to see bacterial growth on the plate, and if you do not, it is an indication that something in your experimental set-up is preventing the growth of bacteria.

What is a negative control control?

A negative control is a group in an experiment that does not receive any type of treatment and, therefore, should not show any change during the experiment. It is used to control unknown variables during the experiment and to give the scientist something to compare with the test group.

Why use positive and negative controls?

The negative control is used to show that any positive effects of the new treatment aren’t the result of the placebo effect. The positive control is used to detect any problems with the experiment and to benchmark results against another medication.

When should a positive control be used?

A positive control is a group in an experiment that receives a treatment with a known result, and therefore should show a particular change during the experiment. It is used to control for unknown variables during the experiment and to give the scientist something to compare with the test group.

What are the two types of negative control?

We distinguish two types of negative controls (exposure controls and outcome controls), describe examples of each type from the epidemiologic literature, and identify the conditions for the use of such negative controls to detect confounding.

Why are positive controls important?

For scientists, positive controls are very helpful because it allows us to be sure that our experimental set-up is working properly. For example, suppose we want to test how well a new drug works and we have designed a laboratory test to do this.

When should a negative control be used?

It involves testing the experiment with something that you know will have no effect on it. This helps the analyst compare the result to a new experiment against an already results that are already known. Negative controls are always used during microbiology testing.