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Sample, Reliability, and Validity


The target population will be adults diagnosed with depression aged between 18 and 65 years. The sample will include equal numbers of male and female participants to ensure generalizability. Participants will be people with a clinical diagnosis of depression and already taking antidepressants. Therefore, purposive sampling will be used to obtain the sample population. At least 60 participants will be randomized to the intervention and control group (30 participants each). The target sample is appropriate for this study because they have a clinical diagnosis of depression. The purpose of this study is to determine the effect of progressive muscle relaxation (PMR) in addition to antidepressants and hence recruiting adults with depression is appropriate for the study.


Patients will be randomized to intervention and control group and data collection will be through the patient Health Questionnaire—9 (PHQ-9). Data will be collected before and after the intervention. Before starting PMR on the intervention group, the severity of depression will be assessed in both groups using the PHQ-9. After the intervention, severity will be assessed again. The tool is administered by the clinician and is a short (30-minutes) assessment of depression and patient wellbeing outcomes. Levis et al. (2019) reported a test-retest reliability of 0.74 for this tool. The tool has been validated and hence is reliable in evaluating depression.


The PHQ-9 is also a valid tool for data collection on depression severity. It has been validated in various studies and found to have a high level of validity. In one study by Maroufizadeh et al. (2019), the tool had an internal consistency of 0.84 and strong convergent validity when compared with other tools for depression severity. Therefore, the tool will be employed in the study. The target sample is adults with depression and the tool has been validated for this sample.



Levis, B., Benedetti, A., & Thombs, B. D. (2019). Accuracy of Patient Health Questionnaire-9 (PHQ-9) for screening to detect major depression: Individual participant data meta-analysis. BMJ365.

Maroufizadeh, S., Omani-Samani, R., Almasi-Hashiani, A., Amini, P., & Sepidarkish, M. (2019). The reliability and validity of the Patient Health Questionnaire-9 (PHQ-9) and PHQ-2 in patients with infertility. Reproductive Health16(1), 1-8.

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