Is the Questionnaire reliable?
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Reliability of Questionnaires: An Analysis
Introduction to Questionnaire Reliability
Questionnaires are essential tools in research, particularly in social sciences, for collecting data efficiently. The reliability of a questionnaire refers to its ability to produce consistent and stable results over time and across different populations. This article synthesizes findings from multiple studies to evaluate the reliability of various questionnaires used in different research contexts.
Internal Consistency Reliability
Strengths and Difficulties Questionnaire (SDQ)
The SDQ, used to assess behavioral and emotional problems in children, shows good internal consistency for the total difficulty scale, with Cronbach’s alpha values of 0.79 for parents' versions and 0.82 for teachers' versions. However, the internal consistency for other subscales is weaker, ranging from 0.49 to 0.69 for parents and 0.69 to 0.83 for teachers.
European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30)
The EORTC QLQ-C30 demonstrates good internal reliability for eight out of its nine domains, with Cronbach’s alpha coefficients exceeding 0.70. The Cognitive Functioning domain, however, consistently performs poorly.
Chronic Respiratory Questionnaire (CRQ)
Both the self-administered and interviewer-administered versions of the CRQ show good internal consistency reliability, with Cronbach’s alpha values ranging from 0.73 to 0.89 across different domains.
Mental Health Questionnaires for College Student Athletes
Questionnaires assessing mental health domains such as strain, anxiety, depression, and ADHD among college student athletes exhibit acceptable internal consistency reliability. However, measures for sleep, gambling, and psychosis show questionable reliability, and the eating disorder measure has poor reliability in males and questionable reliability in females.
Patient Health Questionnaire (PHQ-9)
The Chinese version of the PHQ-9, used for depression screening, shows high internal consistency reliability with a Cronbach’s alpha of 0.86.
Test-Retest Reliability
Strengths and Difficulties Questionnaire (SDQ)
The SDQ shows mostly inadequate test-retest reliability, indicating that it may not consistently measure the same constructs over time.
Chronic Respiratory Questionnaire (CRQ)
The CRQ demonstrates good test-retest reliability, with intraclass correlation coefficients ranging from 0.78 to 0.95 for different domains.
Physical Activity Questionnaires for People with Mental Disorders
Self-reported physical activity questionnaires (SRQs) show moderate to good test-retest reliability for assessing various levels of physical activity, with correlations ranging from 0.63 to 0.75.
Patient Health Questionnaire (PHQ-9)
The PHQ-9 also shows high test-retest reliability, with a correlation coefficient of 0.86 over a two-week period.
Inter-Rater Reliability
Strengths and Difficulties Questionnaire (SDQ)
The SDQ shows moderate inter-rater reliability between parents (correlation coefficients ranging from 0.42 to 0.64) and strong inter-rater reliability between teachers (ranging from 0.59 to 0.81). However, cross-informant consistency is weak to moderate, with correlation coefficients ranging from 0.25 to 0.45.
Conclusion
The reliability of questionnaires varies significantly across different tools and contexts. While some questionnaires like the EORTC QLQ-C30 and the PHQ-9 demonstrate high internal consistency and test-retest reliability, others like the SDQ show variability in reliability across different scales and informants. Ensuring the reliability of a questionnaire is crucial for obtaining valid and consistent data, and researchers must carefully evaluate and, if necessary, improve the reliability of their instruments before widespread use.
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