Simon L Turner1, Amalia Karahalios1, Andrew B Forbes1, Monica Taljaard2,3, Jeremy M Grimshaw2,3,4, Elizabeth Korevaar1, Allen C Cheng1,5, Lisa Bero6, Joanne E McKenzie1. 1. School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia. 2. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. 3. School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada. 4. Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada. 5. Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia. 6. Faculty of Medicine and Health, School of Pharmacy and Charles Perkins Centre, The University of Sydney, Sydney, New South Wales, Australia.
Abstract
INTRODUCTION: Interrupted Time Series (ITS) studies may be used to assess the impact of an interruption, such as an intervention or exposure. The data from such studies are particularly amenable to visual display and, when clearly depicted, can readily show the short- and long-term impact of an interruption. Further, well-constructed graphs allow data to be extracted using digitizing software, which can facilitate their inclusion in systematic reviews and meta-analyses. AIM: We provide recommendations for graphing ITS data, examine the properties of plots presented in ITS studies, and provide examples employing our recommendations. METHODS AND RESULTS: Graphing recommendations from seminal data visualization resources were adapted for use with ITS studies. The adapted recommendations cover plotting of data points, trend lines, interruptions, additional lines and general graph components. We assessed whether 217 graphs from recently published (2013-2017) ITS studies met our recommendations and found that 130 graphs (60%) had clearly distinct data points, 100 (46%) had trend lines, and 161 (74%) had a clearly defined interruption. Accurate data extraction (requiring distinct points that align with axis tick marks and labels that allow the points to be interpreted) was possible in only 72 (33%) graphs. CONCLUSION: We found that many ITS graphs did not meet our recommendations and could be improved with simple changes. Our proposed recommendations aim to achieve greater standardization and improvement in the display of ITS data, and facilitate re-use of the data in systematic reviews and meta-analyses.
INTRODUCTION: Interrupted Time Series (ITS) studies may be used to assess the impact of an interruption, such as an intervention or exposure. The data from such studies are particularly amenable to visual display and, when clearly depicted, can readily show the short- and long-term impact of an interruption. Further, well-constructed graphs allow data to be extracted using digitizing software, which can facilitate their inclusion in systematic reviews and meta-analyses. AIM: We provide recommendations for graphing ITS data, examine the properties of plots presented in ITS studies, and provide examples employing our recommendations. METHODS AND RESULTS: Graphing recommendations from seminal data visualization resources were adapted for use with ITS studies. The adapted recommendations cover plotting of data points, trend lines, interruptions, additional lines and general graph components. We assessed whether 217 graphs from recently published (2013-2017) ITS studies met our recommendations and found that 130 graphs (60%) had clearly distinct data points, 100 (46%) had trend lines, and 161 (74%) had a clearly defined interruption. Accurate data extraction (requiring distinct points that align with axis tick marks and labels that allow the points to be interpreted) was possible in only 72 (33%) graphs. CONCLUSION: We found that many ITS graphs did not meet our recommendations and could be improved with simple changes. Our proposed recommendations aim to achieve greater standardization and improvement in the display of ITS data, and facilitate re-use of the data in systematic reviews and meta-analyses.
Authors: Alina Weise; Julia Lühnen; Stefanie Bühn; Felicia Steffen; Sandro Zacher; Julia Lauberger; Deha Murat Ates; Andreas Böhmer; Henning Rosenau; Anke Steckelberg; Tim Mathes Journal: Pilot Feasibility Stud Date: 2021-05-13
Authors: Simon L Turner; Amalia Karahalios; Andrew B Forbes; Monica Taljaard; Jeremy M Grimshaw; Joanne E McKenzie Journal: BMC Med Res Methodol Date: 2021-06-26 Impact factor: 4.615
Authors: Sarah L Alderson; Tracey M Farragher; Thomas A Willis; Paul Carder; Stella Johnson; Robbie Foy Journal: PLoS Med Date: 2021-10-04 Impact factor: 11.069