Experiment

From Latin ex- + -periri (akin to periculum attempt).

An experiment in baking

As a simple example, consider that many bakers have noticed that the amount of "fluffiness" in a loaf of bread seems to be related to how much humidity there is in the air when the dough is being made. This can be formalized as the hypothesis: "all other things being considered equal, the greater the humidity, the fluffier the bread".

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While this hypothesis might arise naturally from baking many loaves over time, an experiment to determine whether or not this is really true would be to carefully prepare bread dough, as identically as possible, on two types of days: days when the humidity is high, and days when the humidity is low. If the hypothesis is true, then the bread prepared on the high humidity days should be fluffier.

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Several features of this experiment hold in general for all experiments:

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• We must try to make all other conditions of the process to be as similar as possible between the trials. For example, the amounts of flour and water added, the temperature of the butter, and the amount of kneading all may have an effect on the fluffiness; so the experiment should explicitly attempt to control the other variables which could have an effect on the outcome. This gives us some confidence in the statement "all other things being equal,...".
• Although "fluffiness" may seem to be an easily understood idea, one baker's idea of "fluffy bread" may be different than another baker's. The experiment must be based on objective quantities - for example "fluffiness is measured as the total volume of the loaf of bread from one pound of flour". This idea, coupled with the exactness of the description of how the experiment is to be performed, is sometimes called the operational aspect of the experiment; the idea that all actions, quantities, and observations can be agreed upon by reasonable people.
• Noting that once, on a humid day, one baked a fluffy loaf is not enough. The experiment should be repeatable; given that one performs the experiment exactly as described, one should expect to see the same results, no matter who performs the experiment or how many times it is performed.

:Repeatability of an experiment helps to eliminate various types of experimental errors - one may think that one has accurately described all of the relevant techniques and measurements in an experiment, but certain other effects (such as the brand of the flour, trace impurities in the water used in the dough, etc.) may actually be contributing to the observed effects. In the scientific method, someone may claim that they have performed an experiment with a particular result, and thereby supported a particular hypothesis. However, until other scientists have performed the same experiment in the same way and gotten the same results, the experiment is usually not considered as a "proven" result (see cold fusion for a recent example).

Related Topics:
Experimental error - Cold fusion

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• Finally, even though one has baked bread a hundred times, occasionally a loaf will completely fail "because the kitchen gods are unhappy". It is important to realize that some hypotheses cannot be tested experimentally - since we cannot make a measurement which will tell us whether or not the "kitchen gods" are "happy", we cannot perform an experiment which either proves or disproves the hypothesis "the best bread happens when the kitchen gods are happy".