1 ISE 311 Ch. 19 Chapter 19: Error Reduction ERROR: An event when an action other than desired takes place. Sequence: Consider accidents to be predictable and preventable.  i.e., break the sequence Normality  error  accident  minor loss  major loss  catastrophe

2 ISE 311 Ch. 19 Error reduction  cognitive ergonomics. Justifications of ergonomics center around …  Reduction of physical stress  Reduction of errors (waste) Benefits of reducing errors  Improves safety  Improves quality  Improves productivity

3 ISE 311 Ch. 19 Causes of Errors Poor design of equipment Poor management of equipment Poor procedures Poor training Other factors

4 ISE 311 Ch. 19 Errors in the Workplace Costs  Range from seconds of time to injury and death.  Include cleanup, fines, loss of market share, legal costs.  Are difficult to quantify.  Are often concealed.  Are perceived unequally.

5 ISE 311 Ch. 19 Errors in the Workplace Reduce costs by  Give more attention to problems where potential cost is higher.  Be a scientist, not an advocate.  Seek root causes, not blame.  Avoid punishment.

6 ISE 311 Ch. 19 Types of Errors Omission or commission Type 1 or Type 2 System or measurement (of the system)  Observed error = System + Measurement Perception, decision, or action Slip vs mistake  Slip: non-deliberate failure to follow rule  Mistake: Conscious planning results in unanticipated action Failure of knowledge Malice: deliberate violation of rules or procedures

7 ISE 311 Ch. 19 Error Analysis Techniques Checklists FMEA / FMECA Decision structure tables Fish diagrams Fault trees

8 ISE 311 Ch. 19 Making Decisions/Actions in Public Eliminating privacy can eliminate many errors. Add lighting or move objects/people to visible places. Require approval for deviations from policy. Increase the number of required decision makers. Decisions tend to be slower but better quality. Exceptions:  Emergency situations  High risk environments

9 ISE 311 Ch. 19 Guideline 1: Get Enough Information Generate relevant information.  May be difficult if information is subjective.  Provide additional information for novices. Ensure information reception.  Be sure people know how to get and use information.  Be sure novices know how to find it.

10 ISE 311 Ch. 19 Guideline 2: Ensure That Information Is Understood Communicating with the general public is more difficult than with employees. For directions, use a series of signs instead of maps. For maps, use “track up” rather than north. Translate and standardize words. Avoid double negatives. Field-test procedures. Use information feedback.

11 ISE 311 Ch. 19 Guideline 3: Have Proper Equipment / Procedures / Skill Equipment  Design  Amount  Arrangement  Maintenance Procedures  Computer procedures  Human procedures Skill  Consider skill of machine vs. person.  Do not assume a fully capable and trained operator.  Provide job aids and refresher training.  Novices make more errors than experienced operators.

12 ISE 311 Ch. 19 Guideline 4: Don’t Forget Reduce the need to remember.  Avoid verbal orders.  Make a list.  Do it now.  Have standard places for things. Use memory aids.  Make them complete, convenient, and accessible.  Use forms to indicate when information is missing.  Consider downsides.  Create a pattern or standard sequence.  Use calendars, appointment cards, and reminders.

13 ISE 311 Ch. 19 Guideline 5: Simplify the Task Improve communication. Field-test instructions. Use all-letter or all-numeric codes. Avoid complex words. Emphasize important information. Let the operator filter information.

14 ISE 311 Ch. 19 Guideline 6: Allow Enough Time Too little time results in stress and errors. Time stress is one stress than can be reduced. Assign additional staff when necessary. Cross-train employees to provide flexibility.

15 ISE 311 Ch. 19 Guideline 7: Have Sufficient Motivation /Attention Motivation  Motivation is not a substitute for engineering.  Social pressure can help or hinder performance.  What motivates people is not always obvious. Attention  Lack of sleep and substance abuse may cause lapses.  For critical decisions and actions, minimize distractions.

16 ISE 311 Ch. 19 Guideline 8: Give Immediate Feedback Calibrate instruments periodically. Use closed-loop systems. Notify the operator when an error has been corrected. Make error messages specific and understandable. Consider that operators may disable alarms. Reduce delay between error and detection.

17 ISE 311 Ch. 19 Error Message Guidelines Try to reduce or eliminate the need for them. Be specific and precise. Be positive and constructive. Be consistent in language use and display format. Use user-centered phrasing. Test their usability.

18 ISE 311 Ch. 19 Guideline 9: Improve Error Detectability Amplify the signal:  Match it to enable paired comparison.  Do not contradict population stereotypes.  Consider location and time. Reduce the noise.

19 ISE 311 Ch. 19 Guideline 10: Minimize Consequences of Errors Make important decisions or actions multi-step and reversible. Make equipment and procedures fail-safe. Consider ease of recovery. Ensure recovery does not cause additional problems. Minimize spread of the error through the system. Provide guards.

20 ISE 311 Ch. 19 Inspection Can be manual, fully automatic, or semiautomatic. Inspect all items for one characteristic at a time. For searches, consider task, environment, and personnel factors. Train inspectors and provide an inspection manual. Inspection Workstations  Consider replacing microscopes with video cameras.  Use an appropriate colored background.  Make chair, work surface, and lighting adjustable.