Here is the design of a clinical trial:

Official Title: Measuring the Prevalence of Nocturnal Cough in Asthmatics by Means of Smartphone-enabled Acoustic Recording and Evaluating the Potential of Nocturnal Cough Rate as a Prognostic Marker for Asthma Control: An Observational Two-Stage Study

Included conditions:
- Asthma
- Cough

Study Armgroups:

Interventions:
- {'type': 'DEVICE', 'name': 'The patient will undergo no intervention', 'description': 'Night coughs will be monitored using smartphone a app and interpreted using machine learning algorithm.'}

Primary Outcomes:
- {'measure': 'Coughs per night assessed by smartphone audio recording', 'description': 'Number of coughs per night measured by means of smartphone audio recording', 'timeFrame': '28 days'}

Please estimate the sample size based on the assumption: 
Power of 80%, significance level of 5%, and a dropout rate of 10%.
Sample size
        The study is powered with regard to the primary endpoint of the second stage. The required sample size was calculated based on the results of Marsden et al.7 That is, a correlation of r=0.30 between nocturnal cough frequency and asthma control was set as the expected strength of correlation. In order to ensure a power (1-Ã) of 80% with a two-tailed type 1-error probability (Î±) of 5% for rejecting a zero bivariate correlation,16 85 participants are required. In terms of parameter accuracy estimation,17 this sample size would result in a 95% CI for the above-mentioned correlation of [0.09, 0.48].
        A dropout rate of 10% is assumed, thus 94 participants will be recruited. To the best knowledge of the authors, no research that investigated the relationship of nocturnal cough, sleep quality and asthma control in a longitudinal setting is available hitherto. This prohibits a more precise evidence-based estimation of the required sample size. Consequently, the required sample size calculation does not take sleep quality and the longitudinal data structure into account. However, due to the comparable strength of association between sleep quality and asthma control (r=0.31â0.36)6 and nocturnal cough and asthma control (r=0.30),7 the required sample size holds for this relationship, too.