Safety / Performance Assessments
A product's risk may be inherent in its design, attributable to particular components or processes used in its manufacture, or associated with specific conditions of use by consumers. Exponent consultants assist clients in assessing safety and performance at all stages of a product's life cycle.
Risks attributable to product design are essentially the same for every product produced. They are not related to a production period, production location, or particular batches or raw materials. During the product development phase, design risk is evaluated statistically through experimental design, failure modes and effects analysis (FMEA), and the estimation of risks associated with components and subsystems.
Exponent statisticians consult with product safety engineers during the product design or manufacturing cycle to try to estimate the risk of accident or injury that might be associated with the use of a product. We work as an independent third party, with manufacturers, to analyze potential risks prior to bringing their product to market.
Variability in the quality of raw material, inadequate quality control, changes in production method, inadequate maintenance, and many other factors can produce variations in product quality and may result in product that does not meet design specifications.
Statistical analysis of the patterns of complaints, or of product yield, can be used to optimize the manufacturing process.
When manufacturing problems arise, our statisticians are typically asked to answer two types of questions:
- What factors are related to the risk of product failure, and during what time period were these factors in play?
- For product already produced, how many additional field failures are expected, and what is the risk of injury associated with these failures?
Product Use by Consumers
For products already in use, field performance data are used for statistical evaluation of safety performance. Field performance is the record of accidents and injuries associated with the product during use by the population of product users. Field performance analysis includes intended uses and misuses of the product (i.e., the product is evaluated under the conditions in which it is actually used). Typical sources of field performance data are administrative databases, such as warranty claims data, complaint data, police accident-report data, and fire department report data. Evaluating the safety of a product requires estimation of accident or injury rates (i.e., the number of accidents or injuries per million products produced, or per million products produced per year of use). Sources of this exposure information include production and shipment records, data on expected product life, data on length of warranty, and published information on the number of products in use or the number of households that use the product.
Risk/benefit analysis and comparative risk assessments are useful for evaluating product design risk. How well does the product perform compared to similar products (peer products) available to the public in the same time period? Do the benefits of the product outweigh any side effects or safety risks? For recreational products, the comparison is often made on a per-hour-of-use basis, and compared to other recreational activities and products. In some situations (e.g., passenger vehicle crashworthiness), the risk of injury in an accident is used as a measure of the safety of the product, rather than incidents per million products in use. In this case, the rate of injuries per person involved in an accident with the product is compared to the rate of injuries per accident-involved person for peer products.
Safety and performance studies are used to help manufacturers decide on appropriate actions, such as scrapping or recalling the product, issuing consumer notifications, making process changes, or changing product-testing practices.