On your computer screen, you have created a document with four terms: Error. Defect. Deviation. Nonconformity. The next moment, an employee inputs the wrong delivery date, a finished package has a torn seal, a piece of equipment reads a temperature out of the normal range, and a required inspection record is missing. In quality management, all four terms describe issues, yet they are not the same thing. When you understand how to separate each term, it becomes easier to document the problem accurately and to select an appropriate corrective action.
Error
An error is a wrong action. It can be wrong decision. It can be wrong data entry. It can be wrong calculation. For example, when you enter 41 and not 14 in the system, or select an incorrect item code, or when you miss out on performing an obligatory step in the process, you have made an error. Error tells you that what you did or what you didn’t do in fact turned out to be incorrect. Error does not say why this occurred. Error does not tell us that a person acted carelessly. Error is not a synonym of carelessness. Your error may have been influenced by inadequate work instructions, similar parts numbering, incomplete instructions, workload, and software design.
Defect
A defect is an unacceptable product of some service or document. A defect can take place to a finished component, to a piece of the paperwork, to a package label, to a service request. For instance, if one of the items has a crack, if a document is incomplete, if a label is too hard to be legible or has a wrong data, or if you finished a service request without accomplishing the needed work. You made an error, which resulted in a defect. This does not mean that you are the same issue. If you enter wrong size for an order item, this is an error. If you made or you sent an item of wrong size because of the error, it is a defect.
Deviation
Deviation is a situation where something changed. It can happen at any point: in the process, in the equipment setting, in the procedure, or just outside the norm, or any time before you see the defect. For example, the processing time is forty minutes, which is higher than twenty to thirty minutes. If a material may be stored outside the defined temperature range, the condition for this is that the required temperature should be within a range. A deviation says that it was not the case we were looking for. We do not yet know what to do. But we should perform additional verification.
Nonconformity
A nonconformity is an event in which you do not satisfy a requirement. A requirement can appear in an acceptance criteria, procedure, instruction, specifications, or customer expectations. If the signature from an approving person is not present at the document while procedure requires the presence of such signature. There is a nonconformity. If you personally find the color of a package not acceptable, yet you do not find it to be nonconformity as you are not aware if this is specified in an approved requirement. A nonconformity cannot be assumed by what you believe. Instead it must be based on an approved requirement.
All four events may occur simultaneously in the same case. For example, an employee can make an error by selecting a wrong label, create a defect on a package which is also a nonconformity according to the labeling requirement. There is also a deviation as the verification step has not been followed. When recording this event in the report, describe each one separately: what was done wrong, what was the result to the output, what changed from the baseline, and what requirement was not met. If you make it clearer what is what in your record, you will have an easier time to select appropriate evidences, to identify root cause, and to find proper response for quality issues that have nothing to do with each other.