Jump to navigation Jump to search For the book, see The Design of Experiments. Please help improve it or blank outline research paper these issues on the talk page. This article needs additional citations for verification.
This article possibly contains original research. In its simplest form, an experiment aims at predicting the outcome by introducing a change of the preconditions, which is represented by one or more independent variables, also referred to as “input variables” or “predictor variables. Main concerns in experimental design include the establishment of validity, reliability, and replicability. Correctly designed experiments advance knowledge in the natural and social sciences and engineering. Other applications include marketing and policy making. This section possibly contains original research.
This section relies too much on references to primary sources. In 1747, while serving as surgeon on HMS Salisbury, James Lind carried out a systematic clinical trial to compare remedies for scurvy. Lind selected 12 men from the ship, all suffering from scurvy. Lind limited his subjects to men who “were as similar as I could have them,” that is, he provided strict entry requirements to reduce extraneous variation. He divided them into six pairs, giving each pair different supplements to their basic diet for two weeks.
A quart of cider every day. One half-pint of seawater every day. A mixture of garlic, mustard, and horseradish in a lump the size of a nutmeg. Two spoonfuls of vinegar three times a day.