Questions and Answers
What does reliability refer to in psychological assessment?
Consistency in measurement.
What is the reliability coefficient?
True or False: Variance from true differences is considered error variance.
False
Which of the following is NOT one of the three approaches to estimating reliability?
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In the context of test-retest reliability, what is the coefficient often referred to as after 6 months?
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What can be a source of error variance in psychological assessments?
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What does the parallel-forms reliability coefficient measure?
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Study Notes
Understanding Reliability
- Reliability indicates consistency in measurement, reflecting the degree to which a test yields stable and consistent results.
- The reliability coefficient measures the ratio of true score variance to total variance, providing an index of reliability.
Sources of Error Variance
- Scorers and scoring systems can introduce error variance.
- Error sources include forgetting, misunderstanding instructions, and reporting biases (underreporting or overreporting).
Reliability Estimates
- Reliability can be estimated through three approaches:
- Test-retest: Compares scores of the same individuals on two separate test administrations.
- Alternate or parallel forms: Assesses consistency between different test versions measuring the same ability.
- Internal or inter-item consistency: Evaluates the consistency of responses across items within the same test.
Test-Retest Reliability
- Best suited for stable abilities (e.g., personality traits) over time.
- Increased time between tests may lower reliability coefficients; typically, intervals over six months denote the coefficient of stability.
Impact of Test Administration and Environment
- Test construction variations impact reliability; effectively sampling items is crucial.
- Test environment factors (temperature, lighting, noise) can influence results, particularly in tests assessing perceptual judgments.
Testtaker Variables
- Factors such as emotional state, physical health, sleep quality, and medications can affect test performance and reliability.
Examiner-Related Variables
- The examiner's demeanor and appearance, as well as the interaction with the examinee, may also introduce variability in test scores.
Parallel-Forms and Alternate-Forms Reliability
- Evaluated through the degree of similarity between different forms of a test, calculated via an alternate-forms reliability coefficient.
- Steps to assess include dividing the test into equivalent halves and calculating the Pearson correlation coefficient between the scores.
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Description
Explore the critical concept of reliability in psychological assessment. This lesson focuses on various sources of error variance, including scorers and scoring systems, and highlights how they can affect measurement consistency. Understand the significance of reliability in ensuring valid and accurate psychological testing.
