Here is the design of a clinical trial:

Official Title: Fecal Microbiota Transplantation in Chronic Fatigue Syndrome - an RCT

Included conditions:
- Chronic Fatigue Syndrome
- Myalgic Encephalomyelitis

Study Armgroups:
- {'label': 'Preprocessed thawed donor FMT', 'type': 'EXPERIMENTAL', 'description': 'The active transplants are processed in a 2-3 weeks period before treatment of the first participant. Fifty to eighty grams of freshly delivered feces from donors is mixed with 100 mL isotonic saline and 25 mL 85% glycerol, homogenized and poured through a 0.5 mm mesh steel strainer, and transferred to 60 ml luerlock syringes and stored at -40°C.\n\nFrozen transplants are slowly thawed 2 hours prior to administration by transferring the FMT-syringes to a waterbath (+30°C). The transplant is then mixed with 125 mL 12°C isotonic saline in an enema bag prior to installation.', 'interventionNames': ['Biological: Preprocessed thawed donor FMT']}
- {'label': 'Preprocessed thawed autologous FMT', 'type': 'PLACEBO_COMPARATOR', 'description': 'The placebo transplant from each participant is prepared during the inclusion process four to six weeks before intervention and stored at -40°C. Fifty to eighty grams of freshly delivered feces from participants is mixed with 100 mL isotonic saline and 25 mL 85% glycerol is homogenized and poured through a 0.5 mm mesh steel strainer, and transferred to 60ml Luerlock syringes.\n\nFrozen transplants are slowly thawed 2 hours prior to administration by transferring the Luerlock syringes to a waterbath (+30°C). The transplant is then mixed with 125 mL 12°C isotonic saline in the enema bag prior to installation.', 'interventionNames': ['Biological: Preprocessed thawed autologous FMT']}

Interventions:
- {'type': 'BIOLOGICAL', 'name': 'Preprocessed thawed donor FMT', 'description': 'Delivered as an enema using the same equipment and technique as X-ray of the colon', 'armGroupLabels': ['Preprocessed thawed donor FMT']}
- {'type': 'BIOLOGICAL', 'name': 'Preprocessed thawed autologous FMT', 'description': 'Delivered as an enema using the same equipment and technique as X-ray of the colon', 'armGroupLabels': ['Preprocessed thawed autologous FMT']}

Primary Outcomes:
- {'measure': 'Proportion with treatment success in FSS score in donor versus placebo FMT group. Treatment success is defined as an improvement of more than 1.2 points on the Fatigue Severity Scale (FSS)', 'description': 'Fatigue Severity Scale (FSS) is a self-reported, 9-item fatigue scale. Participants rate all 9 items on a 7-point Likert scale (1-2-3-4-5-6-7) depending on how appropriate they felt the statement applied to them over the preceding week. The total score is calculated by adding up the answer from each item and divide by 9. Lower scores indicate better outcomes. Maximum score is 7.\n\nIn an intention to treat analysis we will categorize participants as responders/non-responders, defining responders as decrease of more than 1,2 to the total baseline score in the FSS at 3 months post FMT by Chi Square. Baseline score will be the average of the two scores from the screening period. Missing values will be regarded as non responders', 'timeFrame': 'Three months after treatment'}

Please estimate the sample size based on the assumption: 
Statistical power of 80% in a balanced two-group design (α=0.05; 1−β = 0.80).
Determination of sample size
          The only published open labelled uncontrolled trial with transplantation of enteric bacteria for ME/CFS reported response rate of approximately 58% from one treatment. If the effect is much less, the clinical significance of FMT as treatment modality is questionable due to the nature of the procedure. There are no reviews of the expected placebo effect in this patient group, and validations of questionnaires to assess symptom severity are sparse. From other RCTs performed in this patient group, the response rates to placebo seems to lie somewhere in between 10% and 30%.62

          Assuming that response rate in the placebo group is either 10%, 20% or 30% and 50% in the treatment group, power analysis (independent proportions in SPSS V.28) yields 20, 39 or 93 participants respectively in each group for a statistical power of 80% in a balanced two-group design (Î±=0.05; 1âÎ² = 0.80). As the change from 20% to 50% response rate going from placebo to treatment would represent a clinically relevant difference, and accounting for a couple of dropouts, we, therefore, plan to include and assign the study treatment or placebo to 80 ME/CFS patients in total.