LCQ LCQ Reliability and Reproducibility 1 — Questions and Answers
Question 1: What statistical measure is commonly used to evaluate the internal consistency of the LCQ?
- Intraclass correlation coefficient (ICC)
- Cronbach's alpha (Correct answer)
- Pearson's r
- Cohen's kappa
Correct answer: Cronbach's alpha
Cronbach's alpha measures how closely related items within the LCQ are to each other, directly assessing internal consistency.
Question 2: What is the generally accepted minimum Cronbach's alpha value for the LCQ to demonstrate adequate internal consistency?
- 0.5
- 0.6
- 0.7 (Correct answer)
- 0.9
Correct answer: 0.7
A Cronbach's alpha of 0.7 or above is the widely accepted threshold indicating adequate internal consistency for a health-related quality-of-life questionnaire.
Question 3: The LCQ demonstrates acceptable internal consistency across which of its domains?
- Physical domain only
- Psychological and social domains only
- Physical and psychological domains only
- All three domains: physical, psychological, and social (Correct answer)
Correct answer: All three domains: physical, psychological, and social
The LCQ demonstrates acceptable internal consistency across all three of its domains—physical, psychological, and social—supporting its construct validity.
Question 4: Which type of reliability assesses whether the LCQ yields consistent scores when completed by the same patient on two separate occasions without any change in clinical condition?
- Inter-rater reliability
- Internal consistency
- Test-retest reliability (Correct answer)
- Content validity
Correct answer: Test-retest reliability
Test-retest reliability evaluates the reproducibility of LCQ scores in clinically stable patients over a defined time interval.
Question 5: What is the typical interval used between administrations in LCQ test-retest reliability studies?
- 24 hours
- 1–2 weeks (Correct answer)
- 1 month
- 3 months
Correct answer: 1–2 weeks
A 1–2 week interval is standard in LCQ reliability studies as it is long enough to reduce recall bias but short enough to ensure clinical stability.
Question 6: Which factor would MOST undermine the test-retest reliability of the LCQ?
- Using a 7-point Likert scale for each item
- Clinical change in the patient's cough between administrations (Correct answer)
- High Cronbach's alpha values across domains
- A large sample size in the study
Correct answer: Clinical change in the patient's cough between administrations
If a patient's condition changes between the two administrations, score differences reflect true clinical change rather than measurement error, invalidating the test-retest comparison.
Question 7: The LCQ was originally validated in which patient population, forming the foundation for its reliability evidence?
- Pediatric patients with chronic cough
- Patients with acute upper respiratory infections
- Adults presenting to a specialist cough clinic (Correct answer)
- Patients with cystic fibrosis exclusively
Correct answer: Adults presenting to a specialist cough clinic
The original LCQ validation by Birring et al. (2003) was conducted in adults attending a specialist cough clinic, establishing foundational reliability and validity data.
LCQ LCQ Reliability and Reproducibility 1
What statistical measure is commonly used to evaluate the internal consistency of the LCQ?