Errors of commission

Errors of commission involve performing an act incorrectly. For example, charging wrong materials to the reactor. 

AO - auxiliary operator, CRO - control room operator, MT - mamtcnance technici ni. UCB - upper confidence hound, LCB - lower confidence bound, OM ern r > i omis >ion. COMM - error of commission, and numbers in parenthcMN an . rr-- i., i -... 

The HEPs are for errors of commission and ch include errors in selecting the control. 

Answer The HRA tree is shown in Figure 15.4.3-1. For error of commission or omission use 1E -1. There are 8 error events, hence, the failure estimate is lE-8/trip. Assuming 600 trips per year, the annual failure probability is 6E-6/y. For 10 years it is 6E-5. This has never occurred to me but the low probability means it is unlikely,... 

Figure 4.4 gives an example of an OAET for events that might follow release of gas from a furnace. In this example a gas leak is the initiating event and an explosion is the final hazard. Each task in the sequence is represented by a node in the tree structure. The possible outcomes of the task are depicted as "success" or "failure" paths leading out of the node. This method of task representation does not consider how alternative actions (errors of commission) could give rise to other critical situations. To overcome such problems, separate OAETs must be constructed to model each particular error of commission. 

OAETs are best suited to represent errors of omission. The important errors of commission (i.e., alternative actions that may be performed) are difficult to include satisfactorily. 

The other main application area for predictive error analysis is in chemical process quantitative risk assessment (CPQRA) as a means of identifying human errors with significant risk consequences. In most cases, the generation of error modes in CPQRA is a somewhat unsystematic process, since it only considers errors that involve the failure to perform some pre-specified function, usually in an emergency (e.g., responding to an alarm within a time interval). The fact that errors of commission can arise as a result of diagnostic failures, or that poor interface design or procedures can also induce errors is rarely considered as part of CPQRA. However, this may be due to the fact that HEA techniques are not widely known in the chemical industry. The application of error analysis in CPQRA will be discussed further in Chapter 5. 

Errors of commission, i.e. operating wrong button, reading wrong display, etc. 

Figure 1 Individual PVT reaction times (msec) for a representative subject undergoing 88 hr (3.67 days) of total sleep deprivation. Reaction times are from the 10-min visual PVT test bouts at 20 00 on each day of deprivation at 12, 36, 60, and 84 hr of sustained wakefulness. Reaction times after presentation of each stimulus are represented by black bars. Blank spaces between reaction times represent false starts (errors of commission). Reaction times > 500 msec are termed performance lapses, or lapses in attention. After 12 hr of wakefulness, reaction times were comparable across the test bout, with no false starts. At 36 hr of wakefulness, there were occasional lapses in attention (RT > 500 msec), with some false starts near the end of the test bout. After 60 hr awake the frequency of performance lapses was increased a few minutes into the performance bout. At 84 hr of sustained wakefulness, there were significantly more lapses of attention, with RTs > 8000 msec, and a greater incidence of false starts. (From Ref. 44.)...

A third limitation of the lapse hypothesis involved its inability to account for errors of commission, which involve responses when no stimulus is present (44). Studies have demonstrated a higher incidence of errors of commission with increasing hours of wakefulness (42,44). Importantly, errors of commission show the same profile of circadian-modulated increases across days of total sleep deprivation that is seen for errors of omission (i.e., lapses) (44). Such errors occur as premature responses during PVT performance, and are represented by blank spaces in between RT bars in Figure 1. After 12 hr of sustained... 

Figure 3 Mean PVT reaction times (msec) and false starts (errors of commission) during 88 hr of total sleep deprivation and 88 hours of sleep deprivation with two 2-hour nap opportunities each day. Subjects in the total sleep deprivation (TSD) group (n = 13) are represented by the open circles. Subjects in the 88-hr sleep deprivation plus two 2-hr nap opportunities (NAP) group (n = 15) are represented by the closed squares. Nap opportunity periods were at 02 45-04 45 and 14 45-16 45 each day. The top panel illustrates mean reaction times ( s.e.m.) for each test bout across the experimental protocol. Subjects in the NAP group demonstrated little variation in reaction times across the experimental period, while subjects in the TSD group experienced significant impairment in performance, reflected in the increasing reaction times as time awake increased, with circadian variation in performance capability evident. The bottom panel illustrates mean number of errors ( s.e.m.) per test bout across the experimental protocol. A similar pattern of performance degradation in this variable was evident for both the NAP and TSD groups. (From Ref. 44.)...

In a placebo-controlled trial of propranolol in 312 patients with diastolic hypertension, 13 tests of cognitive function were assessed at baseline, 3 months, and 12 months (94). Propranolol had no significant effects on 11 of the 13 tests. Compared with placebo, patients taking propranolol had fewer correct responses at 3 months and made more errors of commission. 

Finally, I take full responsibility for any errors of commission or omission that may exist in this volume. 

It has been suggested that the central disorder of ADHD is an impairment of behavioral inhibition of responding to inappropriate external stimuli or distracters (Barkley, 1997). Children with ADHD showed excessive errors of commission and a stronger tendency to respond correctly and in error during a Continuous Performance Task (laboni et al.,... 

Type I error (error of commission) is generally considered worse than Type II error (error of omission). 

Automation is commonly assumed to be safer than manual systems because the hazards associated with the manual systems are eliminated. Inadequate consideration is given to whether new, and maybe even worse, hazards are introduced by the automated system and how to prevent or minimize these new hazards. Hie aviation industry has, for the most part, learned this lesson for cockpit and flight control design, where eliminating errors of commission simply created new errors of omission [181,182] (see chapter 9), but most other industries are far behind in this respect. 

Another useful distinction is between errors of omission and errors of commission. Sarter and Woods [181] note that in older, less complex aircraft cockpits, most pilot errors were errors of commission that occurred as a result of a pilot control action. Because the controller, in this case the pUot, took a direct action, he or she is likely to check that the intended effect of the action has actually occurred. Hie short feedback loops allow the operators to repair most errors before serious consequences result. This type of error is stiU the prevalent one for relatively simple devices. 

The consequences of breakdown in mode awareness were fairly small in these system designs. Operators seemed able to detect and recover from erroneous actions relatively quickly before serious problems resulted. Sarter and Woods conclude that, in most cases, mode confusion in these simpler systems are associated with errors of commission, that is, with errors that require a controller action in order for the problem to occur [181]. Because the human controller has taken an explidt action. 

Errors can be of either commission or omission. Errors of commission typically involve failure to follow procedures, taking a shortcut or making an (incorrect) assumption about the vaUdity of an instrument reading. Errors of omission often occur during the response phase of an incident. For example, an operator may fail to isolate a tank that has already started to overflow. 

In the workplace errors are further sorted into two types, errors of omission and errors of commission. 

An error of commission is performing a function not required, such as unnecessarily repeating a procedural step, adding unnecessary steps to a sequence, or doing an erroneous step. 

The USNRC is currently performing a demonstration project wherein the ATHEANA (a detailed human reliability) methodology is being used to identify the potential for operator actions (e.g., errors of commission and errors of omission) during full power operation for a limited set of conditions at one nuclear power plant. Current NRC plans call for a demonstration application of the ATHEANA methodology to low power and shutdown conditions. 

Error of commission incorrect performance of a system-required task or action, given that the task or action is attempted, or the performance of some extraneous task or action which is not required by the system and which has the potential for contributing to some system-defined failure ... 

The manner in which to model human errors. For instance, the NASA Fault Tree Handbook (paragraph 5.7) advises not to model human errors of commission. ... 

The human errors analyzed in HERA may be committed by individuals or by teams. For this research we have focused on person errors committed by single workers who may be part of a time. Team interactions may influence person errors, but the final error of commission or omission can be linked to a single actor. These person errors are different than team errors where the team agrees upon an erroneous conclusion or agrees to follow an incorrect path. The PSF framework presented is suitable for person errors, including errors in single person decision making, but this framework may need additional modification to include team-based human errors. 

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