Sample Bias in Web-Based Patient-Generated Health Data of Dutch Patients With Gastrointestinal Stromal Tumor: Survey Study

Anne Dirkson   ¹ , MSc ;   Dide den Hollander   ^{2, 3, 4} , MD, PhD ;   Suzan Verberne   ¹ , PhD ;   Ingrid Desar   ⁴ , MD, PhD ;   Olga Husson   ^{2, 3, 5} , MSc, PhD ;   Winette T A van der Graaf   ^{2, 6} , MD, PhD ;   Astrid Oosten   ⁶ , MD, PhD ;   Anna K L Reyners   ⁷ , MD, PhD ;   Neeltje Steeghs   ² , MD, PhD ;   Wouter van Loon   ⁸ , MSc ;   Gerard van Oortmerssen   ^{1, 9} , PhD ;   Hans Gelderblom   ¹⁰ , Prof Dr ;   Wessel Kraaij   ^{1, 11} , Prof Dr Ir

¹ Leiden Institute of Advanced Computer Science, Leiden University, Leiden, The Netherlands

² Department of Medical Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands

³ Department of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands

⁴ Department of Medical Oncology, Radboud University Medical Center, Nijmegen, The Netherlands

⁵ Department of Surgical Oncology, Erasmus Medical Center, Rotterdam, The Netherlands

⁶ Department of Medical Oncology, Erasmus Medical Center, Rotterdam, The Netherlands

⁷ Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands

⁸ Department of Methodology and Statistics, Leiden University, Leiden, The Netherlands

⁹ Sarcoma Patient Advocacy Global Network, Wölfersheim, Germany

¹⁰ Department of Medical Oncology, Leiden University Medical Center, Leiden, The Netherlands

¹¹ The Netherlands Organisation for Applied Scientific Research, Den Haag, The Netherlands