A baker's dozen, also known as 13 in a dozen, is a conversion representing an extra item added to a standard dozen (12 units) to ensure the customer receives a full set, even if some items are defective or missing. This conversion is primarily used in baking and food industries where a dozen is a standard unit of measurement for items like eggs, cookies, or pastries. The baker's dozen is a practical application of the concept of a 'tolerance' in measurement, where a small margin of error is allowed to account for potential discrepancies. In scientific contexts, the baker's dozen can be seen as an example of a 'fudge factor' used to compensate for uncertainties in measurement or calculation.