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Questions and Answers
What is the purpose of assigning numbers to represent the amount of an attribute in measurement?
What is the purpose of assigning numbers to represent the amount of an attribute in measurement?
Which of the following is NOT an advantage of measurement?
Which of the following is NOT an advantage of measurement?
What does the equation 'Obtained score = True score ± Error' represent?
What does the equation 'Obtained score = True score ± Error' represent?
Which type of error is related to external conditions affecting measurement?
Which type of error is related to external conditions affecting measurement?
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How does measurement provide a language for communication?
How does measurement provide a language for communication?
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What type of measurement error occurs when external factors distort the results?
What type of measurement error occurs when external factors distort the results?
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Which of the following statements correctly reflects the reliability of a measurement?
Which of the following statements correctly reflects the reliability of a measurement?
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Which of the following best defines validity in measurement?
Which of the following best defines validity in measurement?
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What is the primary focus of reliability in data measurement?
What is the primary focus of reliability in data measurement?
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Which factor is commonly associated with introducing errors in measurement?
Which factor is commonly associated with introducing errors in measurement?
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Which type of validity ensures that the measurement accurately reflects the concept it intends to measure?
Which type of validity ensures that the measurement accurately reflects the concept it intends to measure?
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What is a crucial strategy to reduce measurement error during data collection?
What is a crucial strategy to reduce measurement error during data collection?
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How can the validity of a measuring instrument be assessed?
How can the validity of a measuring instrument be assessed?
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What is considered an extraneous factor that might affect measurement outcomes?
What is considered an extraneous factor that might affect measurement outcomes?
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Why is it important to ensure that data measurement is both reliable and valid?
Why is it important to ensure that data measurement is both reliable and valid?
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What role does anonymity of questionnaire responses play in reducing measurement error?
What role does anonymity of questionnaire responses play in reducing measurement error?
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What is social desirability bias in self-reports?
What is social desirability bias in self-reports?
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Which of the following best defines acquiescence response?
Which of the following best defines acquiescence response?
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Which of the following factors can influence a person's test score temporarily?
Which of the following factors can influence a person's test score temporarily?
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What type of measurement error is linked to the pressure to respond in a socially acceptable manner?
What type of measurement error is linked to the pressure to respond in a socially acceptable manner?
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Extreme response bias is best described as:
Extreme response bias is best described as:
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Which aspect is not typically associated with response-set biases?
Which aspect is not typically associated with response-set biases?
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In the context of measurement error, which condition could directly affect pulse rate measurements?
In the context of measurement error, which condition could directly affect pulse rate measurements?
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Which of the following is not a type of response-set bias?
Which of the following is not a type of response-set bias?
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Study Notes
Week 6: Quantitative Research (3) - Issues of Validity and Reliability of Instruments
- Quantitative research uses various methods to collect data
- Key data collection methods include:
- Self-report: Participants answer questions (e.g., questionnaires)
- Observation: Direct observation of behavior through visual, auditory, tactile, and other senses
- Bio-physiologic measures: Assess clinical variables (e.g., blood pressure, body temperature, blood glucose)
Data Quality
- Validity is the degree to which a measure measures what it's supposed to measure.
- Reliability measures how consistently a measure yields the same results under similar conditions.
- Data measurement must be both valid and reliable to provide trustworthy answers.
Measurement
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Definition: Assigning numbers to represent amounts of a specific attribute using specific rules.
- Example given: A questionnaire asking parents about their agreement with teenagers having access to contraceptives in school clinics, using a 6-point scale of agreement.
- Advantages: Removes guesswork, obtains precise information, provides language for communication and analysis.
Measurement Error
- Distortion in measurement related to extraneous factors.
- Example given: A patient's anxiety level may be affected by a previous family loss.
- Obtained score = True score ± Error
- True score: The score that would be measured under ideal/perfect conditions (independent variable)
- Error: Distortion caused by extraneous factors (extraneous variable)
Error of Measurement (Cont'd)
- Sources of error include:
- Situational contaminants: Conditions under which data is collected affect scores (e.g., researcher's friendliness, location, temperature, lighting, time of day).
- Example: The anxiety level of a patient in an ICU might be higher than in a meeting room.
- Response-set biases:
- Social desirability: Reporting inaccurately on sensitive topics to present oneself in a favorable light.
- Acquiescence response: Agreeing with all statements regardless of content (e.g., time pressure).
- Extreme responses: Selecting extreme options almost exclusively.
- Transitory personal factors: Temporary states like fatigue, hunger, anxiety, or mood can affect scores.
- Situational contaminants: Conditions under which data is collected affect scores (e.g., researcher's friendliness, location, temperature, lighting, time of day).
Learning Outcomes
- Describe major characteristics of measurement
- Identify measurement error sources
- Define validity and reliability
- Describe dimensions of reliability
- Discuss methods for reliability and validity evaluation
- Interpret meaning of reliability and validity information (e.g., results from surveys)
Reliability
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Stability: The extent to which scores are similar on two separate administrations of the same measure.
- Example: A thermometer registering a patient's temperature in two consecutive readings should be relatively stable.
- Assessed using test-retest reliability, calculated via correlation coefficient. A coefficient close to 1 indicates high stability.
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Internal consistency (homogeneous): The degree to which all parts of the instrument measure the same trait, assessed using Cronbach's alpha.
- Example: A depression scale should have each question measuring a similar level of concern for depression.
- Range: 0.00 – 1.00
- Desirable Level: 0.70-0.90
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Equivalence: The degree to which two or more independent observers or coders agree about scoring.
- Assessed through inter-rater (interobserver) reliability procedure, calculated with methods like Cohen's Kappa (categorical) and Intraclass Correlation Coefficient (ICC) (continuous).
Validity
- Definition: The degree to which an instrument measures what it is supposed to measure.
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Content validity: The extent to which an instrument contains a representative sample of the content or construct being measured, assessed through expert reviews.
- Example: A questionnaire measuring pressure sore risk contains questions about general health, incontinence, activity level, to adequately explore the concept.
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Criterion-related validity: The extent to which an instrument correlates with an external criterion (gold standard) measure.
- Concurrent Validity: Instrument and criterion measure administered simultaneously.
- Predictive Validity: Instrument used to predict a future criterion.
Tips
- Instrument developers thoroughly evaluate reliability and validity through psychometric assessments
- When using existing instruments, select ones with demonstrated high reliability and validity
- Validation is an on-going process and the more evidence supporting the measure's quality, the greater the researchers' confidence in the measure.
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Description
This quiz focuses on the key concepts of validity and reliability in quantitative research. It explores various data collection methods, including self-reports and bio-physiologic measures, and emphasizes the importance of both valid and reliable measurement for ensuring data quality. Test your understanding of these fundamental principles in this essential area of research methodology.