title: Effect of initial conditions on reproducibility of scientific research.
abstract: BACKGROUND
  It is estimated that about half of currently published research cannot be reproduced. Many reasons have been offered as explanations for failure to reproduce scientific research findings- from fraud to the issues related to design, conduct, analysis, or publishing scientific research. We also postulate a sensitive dependency on initial conditions by which small changes can result in the large differences in the research findings when attempted to be reproduced at later times.
  
  
  METHODS
  We employed a simple logistic regression equation to model the effect of covariates on the initial study findings. We then fed the input from the logistic equation into a logistic map function to model stability of the results in repeated experiments over time. We illustrate the approach by modeling effects of different factors on the choice of correct treatment.
  
  
  RESULTS
  We found that reproducibility of the study findings depended both on the initial values of all independent variables and the rate of change in the baseline conditions, the latter being more important. When the changes in the baseline conditions vary by about 3.5 to about 4 in between experiments, no research findings could be reproduced. However, when the rate of change between the experiments is ≤2.5 the results become highly predictable between the experiments.
  
  
  CONCLUSIONS
  Many results cannot be reproduced because of the changes in the initial conditions between the experiments. Better control of the baseline conditions in-between the experiments may help improve reproducibility of scientific findings.
authors.affiliation: University of South Florida, Division for Evidence-based Medicine and Health Outcomes Research, Department of Medicine, Tampa, Florida, USA ; H. Lee Moffitt Cancer Center & Research Institute, Departments of Hematology and Health Outcomes and Behavior, Tampa, Florida, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Djulbegovic
authors.affiliation: Department of Mathematics and Actuarial Science, Indiana University Northwest, Gary, Indiana, USA.
authors.forename: Iztok
authors.initials: I
authors.lastname: Hozo
keywords: initial conditions; reproducibility; scientific research