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A Gift of Fire: Social, Legal, and Ethical Issues for Computers and the Internet

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Error-free software is not possible. Errors are often caused by more than one factor. Errors can be reduced by following good procedures and ... (Election! ... – PowerPoint PPT presentation

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Title: A Gift of Fire: Social, Legal, and Ethical Issues for Computers and the Internet


1
  • A Gift of Fire Social, Legal, and Ethical Issues
    for Computers and the Internet

2
A Gift of Fire
Errors, Failures, and Risks
  • What Can Go Wrong?
  • Case Study The Therac-25
  • Increasing Reliability and Safety
  • Perspectives on Failures, Dependence, Risk, and
    Progress
  • Computer Models

3
What Can Go Wrong?
  • Facts About Computer Errors
  • Error-free software is not possible.
  • Errors are often caused by more than one factor.
  • Errors can be reduced by following good
    procedures and professional practices.

Q How do we distinguish between tolerable or
unavoidable errors in software versus careless
software development?
4
What Can Go Wrong?
  • The Roles of People in Computer-related Problems
  • Computer User
  • At home or work, users should understand the
    limitations of computers and the need for proper
    training and responsible use.
  • Computer Professional
  • Understanding the source and consequences of
    computer failures is valuable when buying,
    developing, or managing a complex system.
  • Educated Member of Society
  • Personal decisions and political, social, and
    ethical decisions depend on understanding
    computer risks.

5
Categories of Computer Errors and Failures
  • Problems for Individuals
  • usually in their role as consumers.
  • Example OCR, Speech Recognition
  • who are incorrectly identified by inaccurate law
    enforcement databases.
  • Wrong identity
  • System Failures
  • affecting large numbers of people and/or costing
    large amounts of money.
  • Subway Control
  • Safety-Critical Applications
  • where people may be injured or killed.
  • Nuclear Station

6
  • Problems for Individuals
  • Billing Errors
  • Lack of tests for inconsistencies and
    inappropriate amounts (HK MTR).
  • Database Accuracy Problems
  • Incorrect information resulting in wrongful
    treatment or acts.
  • Terrorists Database (Brazilian killed by London
    Police)
  • Military Database (Bombing of Chinese Embassy in
    Yugoslavia)

Q Describe a computer error or failure that has
affected you.
7
Causes for Computer Failures
  • Large population. (Mistakes unavoidable)
  • Human common sense not part of automated
    processing. (When in doubt, verify never guess)
  • Overconfidence in the accuracy of data from a
    computer. (User Responsibility GPS is an
    example)
  • Errors in data entry. (Careless? Double Check?)
  • Information not updated or corrected. (Chinese
    Embassy in former Yugoslavia)
  • Lack of accountability for errors. (Whose duty?)

8
  • System Failures
  • Communications
  • Telephone, online, and broadcast services.
  • Business
  • Inventory and management software.
  • Financial
  • Stock exchange, brokerages, banks, etc..
  • Transportation
  • Reservations, ticketing, and baggage handling.

9
  • System Failures (contd)
  • Causes
  • Insufficient testing and debugging time.
  • Significant changes in specifications (during and
    after project begun).
  • Overconfidence in system.
  • Mismanagement of the project.

Q Describe a recent system failure that affected
many people or resulted in a great monetary loss.
10
  • Safety-Critical Applications
  • Military
  • Power Plants
  • Aircraft
  • Trains
  • Automated Factories
  • Medicine
  • others.

11
Causes for Computer Failures (System)
  • Safety-Critical Applications
  • Overconfidence.
  • Lack of override features.
  • Insufficient testing.
  • Sheer complexity of system.
  • Mismanagement.
  • More than one factor can occur at the same time!
  • HK Air Cargo Terminal Case!

Q What activities do you participate in that are
controlled by safety-critical applications?
12
Case Study The Therac-25
  • The Therac-25 was a software-controlled
    radiation-therapy machine used to treat people
    with cancer.
  • Overdoses of radiation
  • Normal dosage is 100200 rads.
  • It is estimated that 13,000 and 25,000 rads were
    given to six people.
  • Three of the six people died.

Q What determines whether the risks associated
with a safety-critical application are acceptable?
13
Case Study The Therac-25
  • Therac-25 Radiation Overdose
  • Multiple Causes
  • Poor safety design.
  • Insufficient testing and debugging.
  • Software errors.
  • Lack of safety interlocks.
  • Overconfidence.
  • Inadequate reporting and investigation of
    accidents.
  • How to Remind us????

14
Increasing Reliability and Safety
  • What Goes Wrong?
  • Computer Systems Fail Because
  • The job they are doing is inherently difficult,
    and
  • The job is done poorly.
  • Compounding the Reliability Issue
  • Developers and users exhibit overconfidence in
    the system.
  • Reused system software may not work in different
    environments.

Q Identify the elements needed as an incentive
to increase reliability and safety.
15
Increasing Reliability and Safety
  • Professional Techniques (Code of Ethics)
  • Follow good software practices.
  • Exhibit professional responsibility at all levels
    of development and use.
  • Construct well-designed user interfaces.
  • Take human factors into account.
  • Include built-in redundancy.
  • Incorporate self-checking where appropriate.
  • Follow good testing principals and techniques.
  • Managers Guide!!

Q What human interface features should be
considered for ordinary business applications?
16
Increasing Reliability and Safety
  • Law and Regulation
  • Criminal and Civil Penalties
  • to recover loss from faulty or unsafe systems.
  • Liability and Civil Laws
  • to provide incentives to produce reliable and
    safe systems.
  • Warranties
  • to guarantee a certain level of quality.
  • Federal or State Regulations
  • to protect the public.
  • IEEE, ACM, HKIE Code

Warranties, Insurance, Damage
17
Increasing Reliability and Safety
  • Law and Regulation (contd)
  • Database Accuracy Enforcement
  • to protect the public from inaccurate information
    maintained by private companies and government.
  • Authority to use/enter/verify/retrieve data
  • Mandatory Licensing of Software Developers
  • to ensure proper training, competency, and
    continuing education.
  • Graded Contractors

Q How can consumers protect themselves from
faulty software?
18
Perspectives on Failures, Dependence, Risk, and
Progress
  • Failures (Unavoidable)
  • What are acceptable rates of failures?
  • How accurate should software be?
  • Dependence (Unavoidable)
  • How dependent on computer systems are our
    ordinary activities?
  • How useful are computer systems to our ordinary
    activities?
  • Risk and Progress (Minimize Research)
  • How do new technologies become safer?
  • Can progress in software safety keep up with the
    pace of change in computer technology? (Software
    engineering/tools follow hardware progress?!)

19
Computer Models
  • Points to Consider
  • Models are simplifications of either physical or
    intangible systems.
  • Those who design and develop models must be
    honest and accurate with results.
  • Computer professionals and the general public
    must be able to evaluate the claims of the
    developers.

Q What problems in your community have been or
could be studied with computer models?
20
Complete Methodology
  • We define a simplified capacity planning
    methodology that covers
  • 1. Business level
  • 2. Customer behavior level
  • 3. Resource level

21
Queueing Theory -- to predict performance
22
C. Workload Forecasting- Example
  • Online auto-buying is watching traffic grow very
    fast
  • Plot the number of weekly sessions
  • Forecast the increase in traffic to the site in
    the future
  • Use regression techniques in Microsoft Excel to
    add a trend line
  • A good fit to the curve is the exponential fit
  • Number of sessions on week 11

23
Computer Models
  • Evaluating Models
  • Why Models Might Not Be Accurate
  • Developers have incomplete knowledge of the
    system being modeled.
  • Data might be incomplete or inaccurate.
  • Power of the computer might be inadequate.
  • Variables are difficult to numerically quantify.
  • Political and economic motivation to distort
    results. (Election!?)

Q For each item above, give an example of a
model or simulation that was inaccurate.
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