Blind Experiment is an experiment in which certain information that could introduce bias in the results is held back from the Subjects or Researchers or the committee monitoring the experiment or any combination of them.
The term blind is used figuratively of the literal idea of blindfolding someone and hence depriving him of certain information. The main purpose of Blind Experiment is to prevent bias whether intentional or unconscious. Similarly in Blind Experiment, the participants (Subjects or Researchers or monitoring committee) are kept ignorant of information that could introduce bias in the results. Bias can cause various errors to creep into the experiment leading to incorrect results. They are of three types:
1. Single-Blind Study: Information that could introduce bias is concealed from participants (subjects) only and experimenters are not withheld from the information. However this kind of experiment faces a risk of experimenter’s bias where researchers can influence behavior of the participants consciously or subconsciously.
2. Double-Blind Study: Neither the participants nor the researchers are in possession of information that could bring in bias in the results. Both the parties are unaware of participants belonging to control group and those belonging to the test group.
3. Triple-Blind Study: This is an extension of the double-blind study , where the committee monitoring the experiment is also unaware of the identity of groups (control or test)
For example: In a test for consumer’s preference towards a taste among various Brands, concealing the identities of the products (Single-Blind) prevents consumers to choose brands that they are familiar with. Further by concealing this information from the researcher (double-blinded), intentional or unintentional cues to the subjects can be avoided.