Here is the design of a clinical trial:

Official Title: Effectiveness of the Internet Attachment-Based Compassion Therapy (iABCT) to Improve the Quality of Life and Well-being in a Population With Chronic Medical Illness.

Included conditions:
- Chronic Medical Illness

Study Armgroups:
- {'label': 'Intervention group: Internet attachment-based compassion therapy (iABCT).', 'type': 'EXPERIMENTAL', 'description': 'The iABCT is a self-applied program based on the attachment theory and the use of compassion meditations. It is composed of 8 modules that have been reformulated to be completely self-applied and include text, images, illustrations, videos, audio with guided meditations, exercises, and homework. Downloadable PDF files will be made available so that users can review them offline. Each module has been optimized to have a duration of 60 and 90 minutes approximately. The entire intervention is estimated to be completed in eight weeks.', 'interventionNames': ['Behavioral: Internet attachment-based compassion therapy (iABCT).']}
- {'label': 'Control group: Waiting list control group.', 'type': 'NO_INTERVENTION', 'description': 'Participants in this condition will be informed that they will have access to the intervention at 3 months (after the intervention group).'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Internet attachment-based compassion therapy (iABCT).', 'description': 'The iABCT is a self-applied program based on the attachment theory and the use of compassion meditations. It is composed of 8 modules that have been reformulated to be completely self-applied and include text, images, illustrations, videos, audio with guided meditations, exercises and homework. Downloadable PDF files will be made available so that users can review them offline. Each module has been optimized to have a duration of 60 and 90 minutes approximately. The entire intervention is estimated to be completed in eight weeks.', 'armGroupLabels': ['Intervention group: Internet attachment-based compassion therapy (iABCT).']}

Primary Outcomes:
- {'measure': 'Changes in quality of life', 'description': 'EuroQol (EQ-5D; Badia et al., 1999). It is a self-report measures composed by five dimensions of functionality in daily-life and three levels of severity (1-3). A higher score in this scale indicates higher severity on the different areas of functioning in daily life.', 'timeFrame': 'Baseline (week 0), 3-month follow-up, 6-month follow-up'}
- {'measure': 'Changes in wellbeing', 'description': 'Pemberton Happiness Index (PHI; Hervás and Vázquez, 2013). The scale includes eleven items related to different domains of remembered well-being (general, hedonic, eudaimonic, and social well-being) and ten items related to experienced well-being (i.e., positive and negative emotional events that possibly happened the day before); the sum of these items produces a combined well-being index that range from 0 to 10. Higher levels indicate higher levels of wellbeing.', 'timeFrame': 'Baseline (week 0), 3-month follow-up, 6-month follow-up'}

Please estimate the sample size based on the assumption: 
statistical power of .80, significance level (Î±) of .05, dropout rate of 30%
Sample size
        The sample will be composed of 68 participants as minimum. The sample size was calculated using the G*Power 3.1.9.7 for Windows program [68]. Estimated sample size was decided based on medium effect sizes (d = 0.4), statistical power of .80 and Î± = .05, indicating a necessary sample of 52 participants [69]. Considering that the dropout rate in Internet-based interventions for the chronic medical ill population is usually around 30%, a target of 34 people per group was set [70â72].