Here is the design of a clinical trial:

Official Title: Cognitive Control Training in Online Problem Gambling: an Online Randomized Controlled Trial Among Non-treatment Seeking Problem Gamblers

Included conditions:
- Pathological Gambling

Study Armgroups:
- {'label': 'Cognitive Training', 'type': 'EXPERIMENTAL', 'description': 'Online Cognitive training on the Scientific Brain Training® (SBT®) platform with optional guidance by phone', 'interventionNames': ['Other: Experimental Group']}
- {'label': 'Online sensorial program', 'type': 'SHAM_COMPARATOR', 'description': 'Online sensorial program on the Scientific Brain Training® (SBT®) platform with optional guidance by phone', 'interventionNames': ['Other: Control Group']}

Interventions:
- {'type': 'OTHER', 'name': 'Experimental Group', 'description': 'Cognitive web-based training : 2 up to 30 minutes sessions a week during 6 weeks. Optional debriefing by a neuropsychologist up to 15 minutes twice a week', 'armGroupLabels': ['Cognitive Training'], 'otherNames': ['Cognitive training with optional guidance by phone']}
- {'type': 'OTHER', 'name': 'Control Group', 'description': 'Sensorial web-based training : 2 up to 30 minutes sessions a week during 6 weeks. Optional debriefing by a neuropsychologist up to 15 minutes twice a week', 'armGroupLabels': ['Online sensorial program']}

Primary Outcomes:
- {'measure': 'The change over 6 weeks in Problem gambling severity index (PGSI)-recent total score, collected by internet', 'description': 'PGSI-recent, a modified version of Problem Gambling Severity Index (PGSI) with a 30 days recall period in patients with problem gambling, at 6 weeks', 'timeFrame': 'Change from baseline at 6 weeks'}

Please estimate the sample size based on the assumption: 
loss to follow-up at 6 weeks: 55% maximum, power of 80%, two-sided type I error rate of 5%
Estimating expected effect sizes and required sample size
        The sample size was based on the following assumptions on the PGSI: between group change difference: 3 points, estimated SD of the change: 5 points, loss to follow-up at 6 weeks: 55% maximum. With a power of 80%, a two-sided type I error rate of 5%, 200 patients must be included (100 in each group).