CTU Medical Statisticians

Dr Sig Johnsen

Senior Medical Statistician

Dr Sig Johnsen is responsible for the team conducting the statistical work at the Surrey CTU.  His work involves the design, planning, analysing and presenting results of complex multi-centre clinical trials, and he works closely with clients to ensure that their statistical requirements are met.

He has a wealth of experience as a statistician within clinical research and works closely with the RDS.

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Dr Jeewaka Mendis

Medical Statistician

Dr Jeewaka Mendis is currently working as a Medical Statistician at the Surrey Clinical Research Centre. He completed his PhD in Medical Statistics at University of Leicester where he developed a novel methodology to design new clinical trials using existing evidence.

He has a particular research interest in evidence synthesis models including Meta-analysis, Meta-Regression, Indirect Comparison and Mixed Treatment Comparisons. The power and sample size calculations are another area of his expertise as well. He has a wealth of experience in analysing data from a range of commercial sectors including agricultural, financial and healthcare.

He completed his BSc Special Degree in Statistics from the University of Colombo in Sri Lanka and gained his MSc in Information Technology from Keele University, UK.


01483 68 3375

Dr Johnsen and Dr Mendis are responsibile for:

- All statistical aspects of clinical trials, from sample sizing, protocol, randomisation, to double programming final statistical output, using SAS
- Statistically supporting staff and students, including teaching basic statistics to non-specialists, the latter mainly to PhD students using SPSS
- Contributing to funding applications by NHS and Higher Education Institution (HEI) staff via the Research Design Service, and associated statistical support
- Statistical consultancy, both inside and outside the University
- Teaching Statistics modules in Surrey Winter/Summer Schools in which the targeted audience is mostly clinicians and clinical academics.

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