title: mHealth Series: mHealth project in Zhao County, rural China - Description of objectives, field site and methods.
abstract: BACKGROUND
  We set up a collaboration between researchers in China and the UK that aimed to explore the use of mHealth in China. This is the first paper in a series of papers on a large mHealth project part of this collaboration. This paper included the aims and objectives of the mHealth project, our field site, and the detailed methods of two studies.
  The field site for this mHealth project was Zhao County, which lies 280 km south of Beijing in Hebei Province, China.
  
  
  METHODS
  WE DESCRIBED THE METHODOLOGY OF TWO STUDIES: (i) a mixed methods study exploring factors influencing sample size calculations for mHealth-based health surveys and (ii) a cross-over study determining validity of an mHealth text messaging data collection tool. The first study used mixed methods, both quantitative and qualitative, including: (i) two surveys with caregivers of young children, (ii) interviews with caregivers, village doctors and participants of the cross-over study, and (iii) researchers' views. We combined data from caregivers, village doctors and researchers to provide an in-depth understanding of factors influencing sample size calculations for mHealth-based health surveys. The second study, a cross-over study, used a randomised cross-over study design to compare the traditional face-to-face survey method to the new text messaging survey method. We assessed data equivalence (intrarater agreement), the amount of information in responses, reasons for giving different responses, the response rate, characteristics of non-responders, and the error rate.
  
  
  CONCLUSIONS
  This paper described the objectives, field site and methods of a large mHealth project part of a collaboration between researchers in China and the UK. The mixed methods study evaluating factors that influence sample size calculations could help future studies with estimating reliable sample sizes. The cross-over study comparing face-to-face and text message survey data collection could help future studies with developing their mHealth tools.
authors.affiliation: Global eHealth Unit, Department of Primary Care and Public Health, Imperial College London, London, UK.
authors.forename: Michelle Helena
authors.initials: MH
authors.lastname: van Velthoven
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Du
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Global eHealth Unit, Department of Primary Care and Public Health, Imperial College London, London, UK.
authors.forename: Azeem
authors.initials: A
authors.lastname: Majeed
authors.affiliation: Centre for Population Health Sciences and Global Health Academy, University of Edinburgh Medical School, Edinburgh, Scotland, UK.
authors.forename: Igor
authors.initials: I
authors.lastname: Rudan
authors.affiliation: Department of Integrated Early Childhood Development, Capital Institute of Paediatrics, Beijing, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Global eHealth Unit, Department of Primary Care and Public Health, Imperial College London, London, UK.
authors.forename: Josip
authors.initials: J
authors.lastname: Car