title: Contact diaries versus wearable proximity sensors in measuring contact patterns at a conference: method comparison and participants' attitudes.
abstract: Studies measuring contact networks have helped to improve our understanding of infectious disease transmission. However, several methodological issues are still unresolved, such as which method of contact measurement is the most valid. Further, complete network analysis requires data from most, ideally all, members of a network and, to achieve this, acceptance of the measurement method. We aimed at investigating measurement error by comparing two methods of contact measurement - paper diaries vs. wearable proximity sensors - that were applied concurrently to the same population, and we measured acceptability.
  
  
  
  We investigated the contact network of one day of an epidemiology conference in September 2014. Seventy-six participants wore proximity sensors throughout the day while concurrently recording their contacts with other study participants in a paper-diary; they also reported on method acceptability.
  
  
  
  There were 329 contact reports in the paper diaries, corresponding to 199 contacts, of which 130 were noted by both parties. The sensors recorded 316 contacts, which would have resulted in 632 contact reports if there had been perfect concordance in recording. We estimated the probabilities that a contact was reported in a diary as: P = 72 % for <5 min contact duration (significantly lower than the following, p < 0.05), P = 86 % for 5-15 min, P = 89 % for 15-60 min, and P = 94 % for >60 min. The sets of sensor-measured and self-reported contacts had a large intersection, but neither was a subset of the other. Participants' aggregated contact duration was mostly substantially longer in the diary data than in the sensor data. Twenty percent of respondents (>1 reported contact) stated that filling in the diary was too much work, 25 % of respondents reported difficulties in remembering contacts, and 93 % were comfortable having their conference contacts measured by sensors.
  
  
  
  Reporting and recording were not complete; reporting was particularly incomplete for contacts <5 min. The types of contact that both methods are capable of detecting are partly different. Participants appear to have overestimated the duration of their contacts. Conducting a study with diaries or wearable sensors was acceptable to and mostly easily done by participants. Both methods can be applied meaningfully if their specific limitations are considered and incompleteness is accounted for.
authors.affiliation: NIHR Health Protection Research Unit in Modelling Methodology and MRC Outbreak Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.|Modelling and Economics Unit, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK.
authors.forename: Timo
authors.initials: T
authors.lastname: Smieszek
authors.affiliation: Department for Epidemiology, Helmholtz-Centre for Infection Research, Braunschweig, Germany. stefanie.castell@helmholtz-hzi.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Castell
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, CPT, UMR 7332, Marseille, 13288, France.|Data Science Laboratory, ISI Foundation, Torino, Italy.
authors.forename: Alain
authors.initials: A
authors.lastname: Barrat
authors.affiliation: Data Science Laboratory, ISI Foundation, Torino, Italy.
authors.forename: Ciro
authors.initials: C
authors.lastname: Cattuto
authors.affiliation: NIHR Health Protection Research Unit in Modelling Methodology and MRC Outbreak Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.|Modelling and Economics Unit, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: White
authors.affiliation: Department for Epidemiology, Helmholtz-Centre for Infection Research, Braunschweig, Germany.|Hannover Medical School, Hannover, Germany.
authors.forename: Gérard
authors.initials: G
authors.lastname: Krause
mesh_terms: D056044:Actigraphy / Q000295:instrumentation*; D000328:Adult; D001290:Attitude; D015374:Biosensing Techniques / Q000295:instrumentation*; D003226:Congresses as Topic; D016358:Contact Tracing / Q000379:methods*; D005190:Family; D005260:Female; D000072936:Fitness Trackers; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D063731:Mobile Applications; D057566:Self Report; D012944:Social Support; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Acceptability; Contact diary; Contact network; Infection transmission; Infectious disease; Measurement error; Network epidemiology; Network model; Proximity sensor; RFID