Computing Technology: Errors and Risks

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Questions and Answers

What is a common challenge in producing error-free programs?

Lack of funding for development

Too many developers working on a project

To make programs compatible with old technology

High complexity of most applications (correct)

Which of the following is a factor contributing to individual problems with data in computer systems?

High quality control standards

Data encryption protocols

Manual data entry systems

Large populations that may share names (correct)

What was a primary cause of the baggage system failure at Denver Airport?

High employee turnover rates

Insufficient development time (correct)

Outdated software technology

Inadequate training for staff

What is a significant risk associated with voting systems?

Vulnerability to software manipulation or hacking Signup and view all the answers

What is a primary reason researchers study failures in computer systems?

To learn how to avoid future errors Signup and view all the answers

Which issue could result from automated data processing?

Inaccurate data interpretation in special cases Signup and view all the answers

Which statement describes a contributing factor to system failures?

Changes in specifications after project initiation Signup and view all the answers

What role does overconfidence in data accuracy play in computer system failures?

It can lead to overlooking errors in data entry. Signup and view all the answers

What can lead to system failures due to inadequate consideration during design?

Inadequate consideration of user input errors Signup and view all the answers

Which of the following is a reason for abandoning computer systems?

Extreme flaws in the system Signup and view all the answers

What is a common issue that leads to project failure in computer systems?

Poor management and communication Signup and view all the answers

How can the use of new technology impact computer systems?

Introduces unknown reliability issues Signup and view all the answers

What problem can arise due to interaction with physical devices in computer systems?

Unexpected software behavior Signup and view all the answers

What is a characteristic of legacy systems?

Shallow documentation Signup and view all the answers

Which issue may contribute to overly optimistic expectations in project planning?

Underestimation of time requirements Signup and view all the answers

Which factor is crucial in ensuring safe design and development of computer systems?

Consideration of potential safety risks Signup and view all the answers

What was a major contributing factor to the errors experienced with the Therac-25?

Use of updated software without retesting Signup and view all the answers

Which of the following correctly describes a responsibility for the Therac-25 failures?

The manufacturer, programmers, and clinics all share responsibility Signup and view all the answers

What issue was identified in the operator interface of the Therac-25?

Weaknesses in design causing user confusion Signup and view all the answers

What misconception did the manufacturer of Therac-25 hold regarding the incidents?

Changes made did not address the actual problems Signup and view all the answers

Which of the following problems is not considered a management issue in computer systems?

Insufficient testing post-software reuse Signup and view all the answers

What do massive radiation overdoses from Therac-25 illustrate about software systems?

They signify the importance of thorough testing and verification Signup and view all the answers

What is a common misconception about interpreting results or outputs from computer systems?

Users can fully trust output without verifying Signup and view all the answers

Which action is considered essential when reusing software in new environments?

Re-examining specifications and risks Signup and view all the answers

What action did the FDA take after the fifth accident involving the Therac-25?

Declared the machine defective Signup and view all the answers

What was a notable factor contributing to accidents on other radiation treatment equipment?

Technicians attending leisure activities during treatment Signup and view all the answers

Which of the following is NOT listed as a professional technique to enhance safety?

High-speed programming techniques Signup and view all the answers

What principle is emphasized in high reliability organizations?

Preoccupation with failure Signup and view all the answers

What approach helps in identifying risks in safety-critical applications?

Identifying risks and protecting against them Signup and view all the answers

Which aspect must be understood for effectively implementing software specifications?

The needs of the client Signup and view all the answers

Which of the following does NOT relate to professional responsibility in software engineering?

Ignoring minor design errors Signup and view all the answers

What does complacency in safety-critical systems often lead to?

Heightened risk of accidents Signup and view all the answers

Which of the following characteristics are essential for user interfaces to enhance safety and reliability?

Providing clear instructions and error messages Signup and view all the answers

What is an effect of a workload that is too low for users interacting with a system?

Potentially dangerous situations may arise Signup and view all the answers

What is meant by voting redundancy in computing systems?

Multiple computers perform the same task and validate each other's results Signup and view all the answers

Which type of testing ensures that even small changes in a system are thoroughly evaluated?

Beta testing Signup and view all the answers

What is a primary concern when introducing civil and criminal penalties for system producers?

Providing sufficient incentives for development Signup and view all the answers

How should risks associated with computers be compared?

Against the benefits they provide and other dependency risks Signup and view all the answers

In the context of airplane safety, what is a function of the Traffic Collision Avoidance System (TCAS)?

Preventing certain pilot actions to avoid collisions Signup and view all the answers

What role do independent verification and validation (IV & V) play in reliability when changes to a system are made?

They ensure that all changes have been thoroughly checked and validated Signup and view all the answers

Study Notes

Chapter 8: Errors, Failures, and Risks

Chapter 8 discusses errors, failures, and risks related to computing technology.

What We Will Cover

Failures and errors in computer systems are covered
Case study of the Therac-25
Increasing reliability and safety
Dependence, risk, and progress

Failures and Errors in Computer Systems

Most computer applications are complex, making it virtually impossible to create error-free programs.
Failures are often caused by multiple factors.
Computer professionals must study failures to learn how to avoid them and understand the consequences of poor work.

Problems for Individuals

Billing errors are common.
Data in databases can be inaccurate or misinterpreted.
Large populations where names are shared can cause problems for automated processing.
Automated processing may not recognise special cases.
Overconfidence in data accuracy can lead to errors.
Errors in data entry are frequent.
Accountability for errors is sometimes lacking.

System Failures

Examples include Galaxy IV and Amtrak failures,
Voting systems can experience technical issues, or be rigged to give inaccurate results. Software may be vulnerable to viruses.
Denver Airport's baggage system failed due to various complications, including inadequate development time and last minute specification changes.
Airports in Hong Kong and Kuala Lumpur had problems due to inadequate user input consideration by the designers.
Some system flaws are so serious that systems are abandoned after significant investment.

System Failures - Additional Issues

Systems may suffer from a lack of clearly defined goals and specifications, poor management, and poor communication among involved parties.
Unrealistic expectations set by management regarding time and budgets can contribute to failure.
Using new technology with unknown reliability and issues.
Refusal to acknowledge potential problems early on.

Legacy Systems

Legacy systems – often reliable – are typically inflexible, expensive to replace, and lack proper documentation.

What Goes Wrong?

Design and development problems can lead to software and/or hardware not working as intended.
Inadequacy in design for potential risks, interactions with untested physical devices, software incompatibility, unexpected inputs, confusing user interfaces, insufficient testing of software, reuse of software without proper evaluation, and overconfidence in software.
Management and use issues can be addressed by recognizing errors in data entry, inadequate user training, incorrect interpretation of results, failure to maintain databases up-to-date, and user overconfidence.
Misrepresenting issues, hiding problems, and providing inadequate responses to issues can compound problems.

Reuse of Software

Reusing software needs careful consideration of original specifications, potential dangers, and rigorous testing in the new environment. Examples like the Ariane 5 rocket and "No Fly" lists illustrate this.

Case Study: The Therac-25

The Therac-25 radiation therapy machine delivered massive radiation overdoses, leading to severe injuries and deaths, due to several flawed design choices. Re-used software from older systems contained undetected bugs. Weaknesses in the human-machine interface, and inadequate testing contributed to the problems. The developer should have looked for safety risks but did not. The manufacturer made ineffective changes after an incident, and failed to correct all underlying issues. The FDA ultimately declared the machine defective after a series of accidents.

Increasing Reliability and Safety

Professional techniques such as good software engineering, clear user interfaces, redundancy and self-checking, and rigorous testing are essential.
Management should have clear communication and a 'preoccupation with failure' mindset.
Safety critical systems necessitate proper planning and the identification and mitigation of potential hazards.
Specifications must accurately reflect client needs. Understanding how clients use the system is critical.
User interfaces should provide clear instructions, be consistent, and incorporate input checks.
User feedback is important and systems should behave predictably. Too little workload can be dangerous.
Redundancy, voting redundancy, thorough testing, independent verification and validation, and beta testing improves resilience.

Trust the Human or the Computer System?

The use of systems like the Traffic Collision Avoidance System (TCAS) raises the question of how to balance automation with human intervention. Computer systems sometimes override human control to prevent an event.

Law, Regulation, and Markets

Penalties can incentivize positive practices but potentially stifle creativity.
Regulations can be implemented for safety-critical applications. Licensing requirements are frequently debated.
Responsibility is a critical component to address problems.

Dependence, Risk, and Progress

The growth of technology also brings dependence, issues like computers only being 1 facet of this, as well as electricity. Technology is dependent on other systems (for example, electricity).
New technologies, while making progress, were not always initially safe, and this is recognized to have improved. Improvements have stemmed from accidents and disasters. Comparisons are needed to see the risks of technology against those for other methods as well as the potential benefits.

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Description

This quiz covers Chapter 8 on errors, failures, and risks in computing technology. It includes a case study of the Therac-25 and discusses the importance of increasing reliability and safety in computer systems. Understanding how failures arise and the impact of errors on individuals will also be explored.