Here is the design of a clinical trial:

Official Title: A Phase 2 Study to Investigate the Feasibility and Acceptability of the HOLOBalance System Compared to Standard Care in Older Adults at Risk for Falls: a Multi-site Study

Included conditions:
- Accidental Falls
- Aging
- Vestibular Disorder

Study Armgroups:
- {'label': 'HOLOBalance', 'type': 'EXPERIMENTAL', 'description': 'The experimental arm will use the HOLOBalance tele-rehabilitation system to provide the intervention. Participants will be required to use the HOLOBalance system on a daily basis for the duration of the 8 week study. Although participants will have daily interaction with the HOLOBalance system, they will be free to choose when to complete their exercises.', 'interventionNames': ['Device: HOLOBalance']}
- {'label': 'OTAGO Home Exercise Programme', 'type': 'ACTIVE_COMPARATOR', 'description': 'The comparator for this study is the OTAGO home exercise programme. The OTAGO is a systematic, progressive strength and balance training programme and is supported by a comprehensive workbook that provides written and pictorial instructions for each exercise. The OTAGO is well-established and is widely used in clinical practice in the UK for the management of older adults who fall or have increased risk for falling. It has been shown to be well tolerated in older adults in community settings with good adherence rates, and reduces falls rate in older adults by 35%, with greatest effects observed in frailer older women', 'interventionNames': ['Other: OTAGO Home Exercise Programme']}

Interventions:
- {'type': 'DEVICE', 'name': 'HOLOBalance', 'description': "The HOLOBalance tele-rehabilitation system will be used to deliver an evidence based, multi-sensory balance rehabilitation programme to participants, and will deliver a series of exercises prescribed by an expert balance physiotherapist following an initial balance assessment.\n\nThe HOLOBalance system will use a head mounted augmented reality display to deliver exercises and games to participants and will record task performance via a combination of body worn sensors and a depth camera. The HOLOBalance tele-rehabilitation system will provide feedback to the supervising clinical team regarding task performance, participant usage and user feedback. The system will have daily presence in the users' home with users expected to complete their prescribed rehabilitation on a daily basis, which mirrors the prescribed exercise routines often provided by balance physiotherapists.", 'armGroupLabels': ['HOLOBalance']}
- {'type': 'OTHER', 'name': 'OTAGO Home Exercise Programme', 'description': 'The OTAGO is a systematic, progressive strength and balance training programme and is supported by a comprehensive workbook that provides written and pictorial instructions for each exercise. It is well-established and widely used in clinical practice in the UK, and has been shown to reduce falls rate in older adults by 35-40%. It is well tolerated in older adults in community settings with good adherence rates.The OTAGO has also been used as the standard intervention in previous investigations of MSR interventions in older adults. To match intervention and control interventions, participants in the OTAGO group will be asked to complete the OTAGO programme every day for the duration of the 8 week programme.', 'armGroupLabels': ['OTAGO Home Exercise Programme']}

Primary Outcomes:
- {'measure': 'Acceptability Assessment 1: Recruitment Rate', 'description': 'Assessment of recruitment rate of study (% of eligible participants enrolled)', 'timeFrame': 'Through study completion (12 months)'}
- {'measure': 'Acceptability Assessment 2: Programme Compliance', 'description': 'Comparison of compliance with exercise programmes (% of sessions completed) within the intervention group and a control group undertaking standard practice, home based balance rehabilitation (the OTAGO Home Exercise Programme).', 'timeFrame': 'Through study completion (12 months)'}
- {'measure': 'Acceptability Assessment 3: Drop out rate', 'description': 'Comparison of drop-out rates (%) between the intervention group and a control group undertaking standard practice, home based balance rehabilitation (the OTAGO Home Exercise Programme).', 'timeFrame': 'Through study completion (12 months)'}
- {'measure': 'Acceptability 4: Qualitative interview', 'description': 'Acceptability of HOLOBalance to older adults will be investigated via exit interviews performed within the tele-rehabilitation intervention arm.', 'timeFrame': 'Collected at end of each participants participation in the study (After 8 weeks)'}
- {'measure': 'Feasibility of providing HOLOBalance 1: Monitoring of Adverse and Serious Adverse Events', 'description': "Feasibility will be assessed by documenting adverse events (and SAE's) and adverse device effects (and SADE's).", 'timeFrame': 'Through study completion (12 months)'}
- {'measure': 'Feasibility of providing HOLOBalance 2: Monitoring for deviations from study protocol', 'description': 'Assessment of any deviations from protocol reported logged in the site files using the deviation from protocol form.', 'timeFrame': 'Through study completion (12 months)'}

Please estimate the sample size based on the assumption: 
The study does not specify assumptions on general statistical parameters such as significance level, power, or missing/dropout rate.
Sample size
        This proof-of-concept study will recruit 60 participants per group (ie, total sample size of 120). This will allow the researchers to gain preliminary data on the primary outcomes of safety, feasibility and acceptability of the HOLOBalance intervention. This will also provide sufficient data to explore trends for effectiveness and to allow for sample size estimates to be drawn up for a future trial.