Nonreliability

Nonreliability is the state or condition of lacking reliability, meaning the inability of a system, component, source, or process to perform as consistently or dependably as expected. It can apply to physical devices, software, data, or human judgments. In engineering and operations, reliability is the probability that a system operates without failure over a specified period; nonreliability is the deviation from that expectation or the frequency of failures below the required level.

Measurement uses metrics such as failure rate, mean time between failures (MTBF), and the reliability function R(t). In data and information, nonreliability can refer to errors in accuracy, integrity, timeliness, or verifiability. Evaluations may involve accelerated life testing, field data analysis, audits, and quality controls.

Causes include design flaws, manufacturing variability, material degradation, environmental stress, wear and tear, software bugs, improper maintenance, user error, and data corruption or tampering. Nonreliability undermines safety, availability, and trust, especially in critical infrastructure and consumer products.

Mitigation focuses on reliability engineering and risk management: robust design, redundancy, fault detection, preventive maintenance, testing, quality assurance, and continuous monitoring. For data, validation, checksums, version control, and backups help preserve integrity. For human judgment, standardization and training reduce variability.