In Latin, the word experiment comes from experīmentum, which itself comes from experientia, i.e., an experience or a trial. An experiment is a test under controlled conditions made to either demonstrate a known truth, examine the validity of a hypothesis, or determine the efficacy of something previously untried [1].

Two types of experiments exist:

  1. experimental and
  2. non-experimental studies.
Study design Description
Experimental studies A study is experimental or interventional when control is deliberately exercised over the treatment.

The treatment could be whether payments are tested against automated fraud prevention mechanisms to evaluate whether these mechanisms reduce risk.

Experimental studies are often called A/B tests, trials, or knockouts.
Non-experimental studies In contrast, non-experimental (or observational) studies let nature take its course no control is exercised over the treatment.

Reference

  1. A. Aschengrau and G.R. Seage. Essentials of Epidemiology in
    Public Health. Jones & Bartlett Learning, 2014.
  2. By Rick Doble (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (https://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)]