Errors and Security - PowerPoint PPT Presentation

1 / 10
About This Presentation
Title:

Errors and Security

Description:

Do we measure what we want to measure? Reliability. Do we ... Old Rifle New Rifle New Rifle Sunglare. Low Reliability High Reliability Reliable but Not Valid ... – PowerPoint PPT presentation

Number of Views:18
Avg rating:3.0/5.0
Slides: 11
Provided by: hem3
Category:

less

Transcript and Presenter's Notes

Title: Errors and Security


1
Errors and Security
  • Validity
  • Do we measure what we want to measure?
  • Reliability
  • Do we get the same result each time?
  • Degree of details
  • Accuracy
  • Comparison

2
Validity
  • Concept - Do we measure what we really want to
    measure?
  • Statistical
  • Can we draw conclusions?
  • Internal
  • Historical event
  • Maturity - respondent changes attitudes
  • Selection - wrong respondents
  • Faulty - not at home, invalid responds
  • External
  • Can the results be generalised?

3
Reliability
  • Concept - Can the same results be achieved in
    other circumstances or if another person is
    repeating the observations
  • Equipment
  • The ruler always measure the same distance, but
    the measurement may not be correct
  • Data Collection
  • Is the interviewer reliable?
  • Data processing
  • Coding error?

4
Random sampling error - chapters 15 16
Sample 1
Population
inference
sampling
Sample 2
5
Systematic Sampling Error
  • Sampling bias
  • consistent deviation from true value
  • SSE - also called nonsampling errors
  • Can be explained by
  • Respondent error
  • Administrative error

6
Non Response Error
  • No information at all
  • Nonrespondents - especially mail surveys
  • Not-at-home - when do you call?
  • Refusals - follow up procedures, incentives
  • Incomplete information
  • Refusals
  • Self-selection bias - extreme responses
  • Cultural bias - Copenhagen/Thy

7
Response Bias - p 171
  • Deliberate falsification
  • Unconscious misrepresentation
  • acquiescence bias - always agrees
  • extremity bias - Copenhagen rather than Thy
  • interviewer bias - impress interviewer
  • auspices bias - who is asking (which
    organisation?)
  • social desirability bias - exceed level of salary

8
Administrative error
  • data processing error
  • sample selection error
  • interviewer error
  • interviewer cheating

9
Validity
  • The ability to make sure that a measurement -
    with the help of a scale - actually measures what
    was meant to be be measured.
  • How many times did you visit the hospital last
    year ?

10
Reliabilitet og validitet On Target
Old Rifle New Rifle New Rifle
Sunglare Low Reliability High
Reliability Reliable but Not Valid (Target
A) (Target B) (Target C)
Write a Comment
User Comments (0)
About PowerShow.com