QUALITY BASICS Root Cause Analysis For Beginners

1 QUALITY PROGRESSIJULY 2004I45 Root Cause AnalysisFor Beginnersby James J. Rooney and Lee N. Vanden Heuveloot Cause Analysis (RCA) is a processdesigned for use in investigating and cate-gorizing the root causes of events with safe-ty, health, environmental, QUALITY , reliability andproduction impacts. The term event is used togenerically identify occurrences that produce orhave the potential to produce these types of conse-quences. Simply stated, RCA is a tool designed to helpidentify not only whatand howan event occurred,but also whyit happened. Only when investiga-tors are able to determine why an event or failureoccurred will they be able to specify workablecorrective measures that prevent future events ofthe type observed. Understanding why an event occurred is thekey to developing effective an occurrence during which an opera-tor is instructed to close valve A; instead, theoperator closes valve B.

2 The typical investiga-tion would probably conclude operator errorwas the Cause . This is an accurate description of what hap-pened and how it happened. However, if the ana-lysts stop here, they have not probed deeplyenough to understand the reasons for the , they do not know what to do to pre-vent it from occurring again. In the case of the operator who turned thewrong valve, we are likely to see recommenda-tions such as retrain the operator on the proce-dure, remind all operators to be alert whenRQUALITY BASICSIn 50 WordsOr Less Root Cause Analysis helps identify what, howand why something happened, thus preventingrecurrence. Root causes are underlying, are reasonablyidentifiable, can be controlled by managementand allow for generation of recommendations. The process involves data collection, causecharting, root Cause identification and recom-mendation generation and valves or emphasize to all personnelthat careful attention to the job should be main-tained at all times.

3 Such recommendations do littleto prevent future occurrences. Generally, mistakes do not just happen but canbe traced to some well-defined causes. In the caseof the valve error, we might ask, Was the proce-dure confusing? Were the valves clearly labeled?Was the operator familiar with this particulartask? The answers to these and other questions willhelp determine why the error took place andwhat the organization can do to prevent recur-rence. In the case of the valve error, example recommendations might include revising the procedure or performing procedure validation toensure references to valves match the valve labelsfound in the root causes is the key to preventingsimilar recurrences. An added benefit of an effectiveRCA is that, over time, the root causes identifiedacross the population of occurrences can be used totarget major opportunities for improvement. If, for example, a significant number of analysespoint to procurement inadequacies, then resourcescan be focused on improvement of this managementsystem.

4 Trending of root causes allows developmentof systematic improvements and assessment of theimpact of corrective Although there is substantial debate on the defi-nition of root Cause , we use the following: 1. Root causes are specific underlying Root causes are those that can reasonably Root causes are those management has controlto Root causes are those for which effective rec-ommendations for preventing recurrences canbe causes are underlying causes. The investi-gator s goal should be to identify specific underly-ing causes. The more specific the investigator canbe about why an event occurred, the easier it willbe to arrive at recommendations that will causes are those that can reasonably beidentified. Occurrence investigations must be costbeneficial. It is not practical to keep valuable man-power occupied indefinitely searching for the rootcauses of occurrences.

5 Structured RCA helps ana-lysts get the most out of the time they have invest-ed in the causes are those over which managementhas control. Analysts should avoid using generalcause classifications such as operator error, equip-ment failure or external factor. Such causes are notspecific enough to allow management to makeeffective changes. Management needs to knowexactly why a failure occurred before action can betaken to prevent recurrence. We must also identify a root Cause that manage-ment can influence. Identifying severe weather as the root Cause of parts not being delivered ontime to customers is not appropriate. Severe weath-er is not controlled by causes are those for which effective recom-mendations can be directly address the root causes identifiedduring the investigation. If the analysts arrive atvague recommendations such as, Improve adher-ence to written policies and procedures, then they probably have not found a basic and specificenough Cause and need to expend more effort in theanalysis Major StepsThe RCA is a four-step process involving the fol-lowing: 1.

6 Data Causal factor charting. 46 IJULY BASICSI dentifying severe weather as the root Cause of parts notbeing delivered on time tocustomers is not PROGRESSIJULY 2004I47 Causal Factor ChartFIGURE 1 Aluminum melts, forming hole in panElectricburnershorts outGrease igniteswhen itcontactsburnerFire startson thestoveMary meetswith JaneArcing heatsbottom ofaluminumpanMary leavesthe fryingchicken unattendedJane ringsthe doorbellJane comesto the doorMary beginsfryingchickenMary uses analuminum panCFCFMaryPanJaneJane, MaryMaryBurnerPanPanConclusionMaryMary10 minutesFiregeneratessmokeAssumedMary runsinto thekitchenMarySmokedetectoralarmsJane, MaryAbout 5:10 pmFire extinguisheris notchargedMaryFire extinguisherdoes not operate whenMary tries to use itMaryMary pulls the plug on the fire extinguisherMaryMary seesthe fireon the stoveMaryMary tries to use the fire extinguisherMaryCFHow much oil is used?

7 How much chicken?Chicken, pan, oilWhat exactlydid she see?MaryHad it been previously used?Inspection tagHad it not been originally charged?Fire extinguisherHad it leaked? Fire extinguisher,floorDoes Mary know how to use a fire extinguisher?MaryIs "plug" the sameas pin?MaryPart oneCF = Causal factor5:00 pmFigure 1 continued on next page48 IJULY Root Cause Recommendation generation and implementa-tion. Step one data collection. The first step in theanalysis is to gather data. Without complete infor-mation and an understanding of the event, thecausal factors and root causes associated with theevent cannot be identified. The majority of timespent analyzing an event is spent in gatheringdata. Step two Causal factor charting. Causal factorcharting provides a structure for investigators to orga-nize and analyze the information gathered duringthe investigation and identify gaps and deficienciesin knowledge as the investigation progresses.

8 Thecausal factor chart is simply a sequence diagramwith logic tests that describes the events leading upto an occurrence, plus the conditions surroundingthese events (see Figure 1, p. 47). Preparation of the causal factor chart shouldbegin as soon as investigators start to collect infor-mation about the occurrence. They begin with askeleton chart that is modified as more relevantfacts are uncovered. The causal factor chart shoulddrive the data collection process by identifyingdata needs. Data collection continues until the investigatorsare satisfied with the thoroughness of the chart(and hence are satisfied with the thoroughness ofthe investigation). When the entire occurrence hasbeen charted out, the investigators are in a goodposition to identify the major contributors to theincident, called causal factors . causal factors arethose contributors (human errors and componentfailures) that, if eliminated, would have either pre-vented the occurrence or reduced its severity.

9 In many traditional analyses, the most visiblecausal factor is given all the attention. Rarely, how-ever, is there just one causal factor; events are usu-ally the result of a combination of only one obvious causal factor is addressed,the list of recommendations will likely not be com-plete. Consequently, the occurrence may repeatitself because the organization did not learn all thatit could from the three root Cause identification. After allthe causal factors have been identified, the investi-gators begin root Cause identification. This stepQUALITY BASICSPart twoFire spreads throughout the kitchenKitchen, MaryMary throwswater onthe fireMaryMary calls thefire departmentMary, FDFire departmentarrivesObservationFire departmentputs out fireFD, observationKitchen destroyedby fireOther lossesfrom smoke andwater damage?Time?Time?Time?CFFire was agrease fireMary, panDid she do anything else?

10 MaryWas Mary trying to do this?MaryDid she know this was wrong? Lack of practice fighting fires?MaryWhat is Jane doing during this time?Mary, JaneHow long did it take for the FD to arrive?FD dispatcherDid the FD use the correct techniques?FDQUALITY PROGRESSIJULY 2004I49involves the use of a decision diagram called theRoot Cause Map (see Figure 2, p. 50) to identify theunderlying reason or reasons for each causal factor. The map structures the reasoning process of theinvestigators by helping them answer questionsabout why particular causal factors exist oroccurred. The identification of root causes helpsthe investigator determine the reasons the eventoccurred so the problems surrounding the occur-rence can be addressed. Step four recommendation generation andimplementation. The next step is the generation ofrecommendations. Following identification of theroot causes for a particular causal factor, achievablerecommendations for preventing its recurrence arethen generated.