Verification and Validation are independent procedures that are used together for checking that a product, service, or system meets requirements and specifications and that it fulfills its intended purpose.  These are critical components of a quality management system such as ISO 9000. The words "verification" and "validation" are sometimes preceded with "Independent" (or IV&V), indicating that the verification and validation is to be performed by a disinterestedthird party.
It is sometimes said that validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?"
In practice, the usage of these terms varies. Sometimes they are even used interchangeably.
"Validation. The assurance that a product, service, or system meets the needs of the customer and other identified stakeholders. It often involves acceptance and suitability with external customers. Contrast with verification."
"Verification. The evaluation of whether or not a product, service, or system complies with a regulation, requirement, specification, or imposed condition. It is often an internal process. Contrast with validation."
Verification is intended to check that a product, service, or system (or portion thereof, or set thereof) meets a set of design specifications. In the development phase, verification procedures involve performing special tests to model or simulate a portion, or the entirety, of a product, service or system, then performing a review or analysis of the modeling results. In the post-development phase, verification procedures involve regularly repeating tests devised specifically to ensure that the product, service, or system continues to meet the initial design requirements, specifications, and regulations as time progresses. It is a process that is used to evaluate whether a product, service, or system complies with regulations, specifications, or conditions imposed at the start of a development phase. Verification can be in development, scale-up, or production. This is often an internal process.
Validation is intended to ensure a product, service, or system (or portion thereof, or set thereof) result in a product, service, or system (or portion thereof, or set thereof) that meets the operational needs of the user. For a new development flow or verification flow, validation procedures may involve modeling either flow and using simulations to predict faults or gaps that might lead to invalid or incomplete verification or development of a product, service, or system (or portion thereof, or set thereof). A set of validation requirements (as defined by the user), specifications, and regulations may then be used as a basis for qualifying a development flow or verification flow for a product, service, or system (or portion thereof, or set thereof). Additional validation procedures also include those that are designed specifically to ensure that modifications made to an existing qualified development flow or verification flow will have the effect of producing a product, service, or system (or portion thereof, or set thereof) that meets the initial design requirements, specifications, and regulations; these validations help to keep the flow qualified. It is a process of establishing evidence that provides a high degree of assurance that a product, service, or system accomplishes its intended requirements. This often involves acceptance of fitness for purpose with end users and other product stakeholders. This is often an external process.
It is sometimes said that validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?". "Building the right thing" refers back to the user's needs, while "building it right" checks that the specifications are correctly implemented by the system. In some contexts, it is required to have written requirements for both as well as formal procedures or protocols for determining compliance.
It is entirely possible that a product passes when verified but fails when validated. This can happen when, say, a product is built as per the specifications but the specifications themselves fail to address the user’s needs.
Verification of machinery and equipment usually consists of design qualification (DQ), installation qualification (IQ), operational qualification (OQ), and performance qualification (PQ). DQ is usually a vendor's job. However, DQ can also be performed by the user, by confirming through review and testing that the equipment meets the written acquisition specification. If the relevant document or manuals of machinery/equipment are provided by vendors, the later 3Q needs to be thoroughly performed by the users who work in an industrial regulatory environment. Otherwise, the process of IQ, OQ and PQ is the task of validation. The typical example of such a case could be the loss or absence of vendor's documentation for legacy equipment or do-it-yourself (DIY) assemblies (e.g., cars, computers etc.) and, therefore, users should endeavour to acquire DQ document beforehand. Each template of DQ, IQ, OQ and PQ usually can be found on the internet respectively, whereas the DIY qualifications of machinery/equipment can be assisted either by the vendor's training course materials and tutorials, or by the published guidance books, such as step-by-step series if the acquisition of machinery/equipment is not bundled with on- site qualification services. This kind of the DIY approach is also applicable to the qualifications of software, computer operating systems and a manufacturing process. The most important and critical task as the last step of the activity is to generating and archiving machinery/equipment qualification reports for auditing purposes, if regulatory compliances are mandatory.
Qualification of machinery/equipment is venue dependent, in particular items that are shock sensitive and require balancing or calibration, and re-qualification needs to be conducted once the objects are relocated. The full scales of some equipment qualifications are even time dependent as consumables are used up (i.e. filters) or springs stretch out, requiring recalibration, and hence re-certification is necessary when a specified due time lapse. Re-qualification of machinery/equipment should also be conducted when replacement of parts, or coupling with another device, or installing a new application software and restructuring of the computer which affects especially the pre-settings, such as on BIOS, registry, disk drive partition table, dynamically-linked (shared) libraries, or an ini file etc., have been necessary. In such a situation, the specifications of the parts/devices/software and restructuring proposals should be appended to the qualification document whether the parts/devices/software are genuine or not. Torres and Hyman have discussed the suitability of non genuine parts for clinical use and provided guidelines for equipment users to select appropriate substitutes which are capable to avoid adverse effects. In the case when genuine parts/devices/software are demanded by some of regulatory requirements, then re-qualification does not need to be conducted on the non genuine assemblies. Instead, the asset has to be recycled for non regulatory purposes.
When machinery/equipment qualification is conducted by a standard endorsed third party such as by an ISO standard accredited company for a particular division, the process is called certification. Currently, the coverage of ISO/IEC 15408 certification by an ISO/IEC 27001 accredited organization is limited, the scheme requires a fair amount of efforts to get popularized.
Categories of verification and validation
Validation work can generally be categorized by the following functions:
Prospective validation – the missions conducted before new items are released to make sure the characteristics of the interests which are functioning properly and which meet safety standards. Some examples could be legislative rules, guidelines or proposals, methods, theories/hypothesis/models products and services
Retrospective validation – a process for items that are already in use and distribution or production. The validation is performed against the written specifications or predetermined expectations, based upon their historical data/evidences that are documented/recorded. If any critical data is missing, then the work can not be processed or can only be completed partially. The tasks are considered necessary if:
prospective validation is missing, inadequate or flawed.
the change of legislative regulations or standards affects the compliance of the items being released to the public or market.
reviving of out-of-use items.
Some of the examples could be validation of:
ancient scriptures that remain controversial
Partial validation – often used for research and pilot studies if time is constrained. The most important and significant effects are tested. From an analytical chemistry perspective, those effects are selectivity, accuracy, repeatability, linearity and its range.
Re-validation/Locational or Periodical validation – carried out, for the item of interest that is dismissed, repaired, integrated/coupled, relocated, or after a specified time lapse. Examples of this category could be relicencing/renewing driver's license, recertifying an analytical balance that has been expired or relocated, and even revalidating professionals. Re-validation may also be conducted when/where a change occurs during the courses of activities, such as scientific researches or phases of clinical trial transitions. Examples of these changes could be
out-of-specification] (OOS) investigations, due to the contamination of testing reagents, glasswares, the aging of equipment/devices, or the depreciation of associated assets etc.
In GLP accredited laboratories, verification/revalidation will even be conducted very often against the monographs of the Ph.Eur., IP to cater for multinational needs or USP and BP etc to cater for national needs. These laboratories must have method validation as well.
Concurrent validation – conducted during a routine processing of services, manufacturing or engineering etc. Examples of these could be
System suitability – In a broad way, it usually includes a test of ruggedness among inter-collaborators, or a test of robustness[disambiguation needed] within an organization  However, the U.S. Food and Drug Administration (FDA) has specifically defined it for its administration, as "System suitability testing is an integral part of many analytical procedures. The tests are based on the concept that the equipment, electronics, analytical operations and samples to be analyzed constitute an integral system that can be evaluated as such. System suitability test parameters to be established for a particular procedure depend on the type of procedure being validated". In some cases of analytical chemistry, a system suitability test could be rather a method specific than universal. Such examples are chromatographic analysis, which is usually media (column, paper or mobile solvent) sensitive  However to the date of this writing, this kind of approaches are limited to some of pharmaceutical compendial methods, by which the detecting of impurities, or the quality of the intest analyzed are critical (i.e., life and death). This is probably largely due to
their confinements by the definition of the term defined by different standards.
To solve this kind of difficulties, some regulatory bodies or compendial methods usually provide the advices on what the circumstances or conditions that the performing of a specified system suitability test should be beared and compulsory.
These terms generally apply broadly across industries and institutions. In addition, they may have very specific meanings and requirements for specific products, regulations, and industries. Some examples:
Pharmaceuticals The design, production, and distribution of drugs are highly regulated. This includes software systems. For example in the USA, the Food and Drug Administration have regulations in Part 21 of the Code of Federal Regulations. Nash et al. have published a book which provides a comprehensive coverage on the various validation topics of pharmaceutical manufacturing processes. Some companies are taking a risk-based approach to validating their GAMP system if one understands the regulatory requirements very well while the most of others follows the conventional process  It is a part of GxP management. The aspects of validation and verification are even more intense and emphasized if an OOS occurs. Very often under this circumstance, a multiplicated sample analysis is required for conducting the OOS investigation in a testing laboratory.
^Quinn, James et al.; McDermott, D; Stiell, I; Kohn, M; Wells, G (2006). "Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes". Annals of Emergency Medicine (Elsevier) 47 (5): 448–454. doi:10.1016/j.annemergmed.2005.11.019. PMID16631985.|accessdate= requires |url= (help)
^Sangiovanni, A. et al.; Manini, M; Iavarone, M; Fraquelli, M; Forzenigo, L; Romeo, R; Ronchi, G; Colombo, M (2007). "Prospective validation of AASLD guidelines for the early diagnosis of epatocellular carcinoma in cirrhotic patients". Digestive and Liver Disease (Elsevier) 40 (5): A22–A23. doi:10.1016/j.dld.2007.12.064.|accessdate= requires |url= (help)
^Van Geest-Daalderop, Johanna H. H. et al.; Hutten, Barbara A.; Péquériaux, Nathalie C. V.; Levi, Marcel; Sturk, Augueste (2008). "Improvement in the regulation of the vitamin K antagonist acenocoumarol after a standard initial dose regimen: prospective validation of a prescription model". Journal of Thrombosis and Thrombolysis (Springer) 27: 207. doi:10.1007/s11239-008-0203-4.|accessdate= requires |url= (help)
^Ames, D. et al.; Keogh, A.M.; Adams, J.; Harrigan, S.; Allen, N. (1996). "Prospective validation of the EBAS-DEP — A short sensitive screening instrument for depression in the physically ill elderly". European Psychiatry (Elsevier) 11 (Supplement 4): 361s. doi:10.1016/0924-9338(96)89148-6.|accessdate= requires |url= (help)
^Hart, D.; S.W. Smith (2007). "Retrospective Validation of a Clinical Decision Rule to Safely Rule Out Subarachnoid Hemorrhage in Emergency Department Headache Patients". Annals of Emergency Medicine50 (3): S102–S103. doi:10.1016/j.annemergmed.2007.06.388.Cite uses deprecated parameters (help);|accessdate= requires |url= (help)
^Bressolle, Françoise et al.; Brometpetit, M; Audran, M (1996). "Validation of liquid chromatographic and gas chromatographic methods Applications to pharmacokinetics". Journal of Chromatography B686 (1): 3–10. doi:10.1016/S0378-4347(96)00088-6.|accessdate= requires |url= (help)
^Tollman, Stephen M et al.; Kahn, Kathleen; Sartorius, Benn; Collinson, Mark A; Clark, Samuel J; Garenne, Michel L (2008). "Implications of mortality transition for primary health care in rural South Africa: a population-based surveillance study". Journal of the American Medical Informatics Association372 (9642): 893–901. doi:10.1016/S0140-6736(08)61399-9. PMID18790312.|accessdate= requires |url= (help)
^Heyden, Y. Vander et al.; S.W. Smith (2001). "Guidance for robustness/ruggedness tests in method validation". Journal of Pharmaceutical and Biomedical Analysis (Elsevier) 24 (5–6): 723–753. doi:10.1016/S0731-7085(00)00529-X. PMID11248467.Cite uses deprecated parameters (help);|accessdate= requires |url= (help)
^Ermer, Joachim; John H. McB. Miller (2005). Method Validation in Pharmaceutical Analysis: A Guide to best Practice. Wiley-VCH. p. 418. ISBN3-527-31255-2.Cite uses deprecated parameters (help);|accessdate= requires |url= (help)
^"Calibration of dissolution test apparatus (USP apparatus 1 and 2) – SOP".Missing or empty |url= (help);|accessdate= requires |url= (help)
^Szsz, Gy. et al.; Gyimesi-Forrás, K.; Budvári-Bárány, Zs. (1998). "Optimized and Validated HPLC Methods for Compendial Quality Assessment. III. Testing of Optical Purity Applying 1-Acid-Glycoprotein Stationary Phase". Journal of Liquid Chromatography & Related Technologies21 (16): 2535–2547. doi:10.1080/10826079808003597.|accessdate= requires |url= (help)
^Li, Yong-guo et al.; Chen, M; Chou, GX; Wang, ZT; Hu, ZB (2004). "Ruggedness/robustness evaluation and system suitability test on United States Pharmacopoeia XXVI assay ginsenosides in Asian and American ginseng by high-performance liquid chromatography". Journal of Pharmaceutical and Biomedical Analysis35 (5): 1083–1091. doi:10.1016/j.jpba.2004.04.005. PMID15336355.|accessdate= requires |url= (help)
^Ocampo, Arlene et al.; Lum, Steven; Chow, Frank (2007). "Current challenges for FDA-regulated bioanalytical laboratories for human (BA/BE) studies. Part I: defining the appropriate compliance standards – application of the principles of FDA GLP and FDA GMP to bioanalytical laboratories". The Quality Assurance Journal (John Wiley & Sons) 11 (1): 3–15. doi:10.1002/qaj.399.|accessdate= requires |url= (help)
^Haboudane, Driss et al. (2004). "Hyperspectral vegetation indices and novel algorithms for predicting green LAI of crop canopies: Modeling and validation in the context of precision agriculture". Accreditation and Quality Assurance (Elsevier) 90 (3): 337–352. doi:10.1016/j.rse.2003.12.013.|accessdate= requires |url= (help)