Performance-based approach

In a performance-based approach to quality assurance, a laboratory is free to use its experience to determine the best way to gather and monitor quality assessment data. The quality assessment methods remain the same (duplicate samples, blanks, standards, and spike recoveries) since they provide the necessary information about precision and bias. What the laboratory can control, however, is the frequency with which quality assessment samples are analyzed, and the conditions indicating when an analytical system is no longer in a state of statistical control. Furthermore, a performance-based approach to quality assessment allows a laboratory to determine if an analytical system is in danger of drifting out of statistical control. Corrective measures are then taken before further problems develop. 

The principal tool for performance-based quality assessment is the control chart. In a control chart the results from the analysis of quality assessment samples are plotted in the order in which they are collected, providing a continuous record of the statistical state of the analytical system. Quality assessment data collected over time can be summarized by a mean value and a standard deviation. The fundamental assumption behind the use of a control chart is that quality assessment data will show only random variations around the mean value when the analytical system is in statistical control. When an analytical system moves out of statistical control, the quality assessment data is influenced by additional sources of error, increasing the standard deviation or changing the mean value. 

Control charts were originally developed in the 1920s as a quality assurance tool for the control of manufactured products.Two types of control charts are commonly used in quality assurance a property control chart in which results for single measurements, or the means for several replicate measurements, are plotted sequentially and a precision control chart in which ranges or standard deviations are plotted sequentially. In either case, the control chart consists of a line representing the mean value for the measured property or the precision, and two or more boundary lines whose positions are determined by the precision of the measurement process. The position of the data points about the boundary lines determines whether the system is in statistical control. 

Construction of Property Control Charts The simplest form for a property control chart is a sequence of points, each of which represents a single determination of the property being monitored. To construct the control chart, it is first necessary to determine the mean value of the property and the standard deviation for its measurement. These statistical values are determined using a minimum of 7 to 15 samples (although 30 or more samples are desirable), obtained while the system is known to be under statistical control. The center line (CL) of the control chart is determined by the average of these n points 

The positions of the boundary lines are determined by the standard deviation, S, of the points used to determine the central line 

---

In the previous section we described several internal methods of quality assessment that provide quantitative estimates of the systematic and random errors present in an analytical system. Now we turn our attention to how this numerical information is incorporated into the written directives of a complete quality assurance program. Two approaches to developing quality assurance programs have been described a prescriptive approach, in which an exact method of quality assessment is prescribed and a performance-based approach, in which any form of quality assessment is acceptable, provided that an acceptable level of statistical control can be demonstrated. 

Once a control chart is in use, new quality assessment data should be added at a rate sufficient to ensure that the system remains in statistical control. As with prescriptive approaches to quality assurance, when a quality assessment sample is found to be out of statistical control, all samples analyzed since the last successful verification of statistical control must be reanalyzed. The advantage of a performance-based approach to quality assurance is that a laboratory may use its experience, guided by control charts, to determine the frequency for collecting quality assessment samples. When the system is stable, quality assessment samples can be acquired less frequently. 

The means to a safer and more effective regulatory system is the new safety-focused, performance-based approach being pilot tested by the commission... 

The process hazard analysis required by OSHA PSM is an example of a performance-based approach it allows for a variety of hazard analysis methodologies. A performance-based system requires experts to identify and evaluate all relevant reactive hazards of a process and to determine the complexity of the hazards analysis. If the hazard evaluation demonstrates the possibility of a catastrophic consequence, the process has regulatory coverage. This approach to hazard evaluation allows for both a comprehensive analysis and flexibility in implementation however, if applied to reactive hazards, it requires expertise for implementation and regulatory evaluation. 

It is important that experienced and knowledgeable personnel perform the assessment. Afire risk assessment should be performed by a fire protection engineer who can apply common sense, understand if the results are realistic, and transfer the results into a performance-based approach to fire protection. 

The performance-based approach relies on data needs as criteria for selecting the most appropriate technologically advanced and cost-effective methods of analysis. In a sense, this approach is an extension of the DQO process onto the laboratory. In order to arrive to a decision that a PBMS is needed instead of an existing prescriptive method, we will have to address the following issues ... 

Safe warehousing of chemicals requires a multi-faceted approach that integrates a wide spectrum of issues. Consistent with its scope, the purpose of these Guidelines is to act as a resource for warehouse operators, designers and others concerned with safe warehousing of chemicals using a performance based approach. 

Yih, 2000) Yih, S, et. al.. The Applicability of Applying Risk Informed Performance Based Approach to Digital I C Regulation, NPIC HMIT 2000, Washington DC, Nov. 2000. 

An important benefit of the nonprescriptive/performance-based approach is that an industry can immediately capture what has been found by experience or test to work well—there is no need for the regulators to catch up with the latest technology. 

With the introduction of the internal control regime in the 1980s, it was often stated that, theoretically, the companies safety performance could be checked from their headquarters onshore. According to the regulation, the operator was required to document all relevant safety activities. The essence of the performance-based approach was that companies should have an internal safety system that reduced risk effectively. The underlying idea was that the regulator should focus on whether or not a company had such systems in place, not on the details of how a company achieved its results. 

In a performance-based approach to build structures, all decisions, choices, and tradeoffs start with the required behavior-in-use rather than prescribed solutions for how to meet the stated needs. The supplier responds with an offering that includes the estimated performance of that offering. A validation method, through measurement, calculation, or testing, is necessary to evaluate the performance (over time) and to compare alternative solutions (Szigeti Davis, 2005). The design/build team must warrantee and main-... 

Random failure usually refers to permanent failure due to non-functioning of system components, and these are more related to hardware failure. Probabilistic performance-based approach could be one way to address this. For E/E/PE systems, safety integrity level (SIL) is considered for such purposes. 

Youngblood, R. and Kim, I. June 2005. Issues in formulating performance-based approaches to regulatory oversight of nuclear power plants. Nuclear Engineering and Technology, 37 (3) 231-244. 

Another topic is whether to apply more safety-performance methods during the WS and discussions with the operating company, as supplement to the data-based scenario identification. As commented in the evaluation, the historical data of incidents and events may not reflect the whole risk picture. Positioning failures are less investigated even though they represent major accident potential. Risk based approaches (0ien, 2001) and safety performance based approaches (HSE, 2006, Sklet et al., 2010) could here be a supplement to the barrier and indicator identification. 

Part 3 of EN-Eurocode 8 (CEN 2005a) adopts a fully performance-based approach for the assessment and retrofitting of existing buildings (Fardis 2009). It defines three performance levels (called therein limit states ) ... 

This entry deals with the box behavior of masoiuy structures, which is a major hypothesis for the application of seismic assessment procedures based on the in-plane response of the walls, when using performance-based approaches for seismic safety. A general description is also made of the unreinforced and confined masonry building typologies, regarding the constructive technique, industrial development, and applicability. Methods and procedures are presented for the seismic assessment and safety verification of masOTiiy buildings, which are applied to the case of a dwelling. 

The concept of box behavior and the current performance-based approaches for seismic assessment specified in codes (e.g., EN 1998-1 2004 Sullivan et al. 2012) are explained here referring to cases of unreinforced and confined masonry building structures. In the next two sections, these typologies are presented in general terms. 

A general approach, in which the strategy can be framed, is the performance-based approach that (1) defines a given number of performance levels (PLs), (2) chooses a seismic level for each PL, and (3) requires a given performance for each PL. Examples of PLs are operational, immediate occupancy, life safety, and collapse prevention. 

The performance-based approach delegates the applicator of it the definition or selection of the most appropriate tools to be applied for the... 

A performance-based approach is recommended for seismic evaluation of underground stmctures. Underground stmctures seismic response is controlled by the deformation of the soil or rock medium in which they are embedded and their... 

---