
Restricted mean survival time to estimate an intervention effect in a cluster randomized trial
For time-to-event outcomes, the difference in restricted mean survival time is a measure of the intervention effect, an alternative to the hazard ratio, corresponding to the expected survival duration gain due to the intervention up to a predefined time t*. We extended two existing approaches of restricted mean survival time estimation for independent data to clustered data in the framework of cluster randomized trials: one based on the direct integration of Kaplan-Meier curves and the other based on pseudo-values regression. Then, we conducted a simulation study to assess and compare the statistical performance of the proposed methods, varying the number and size of clusters, the degree of clustering, and the magnitude of the intervention effect under proportional and non-proportional hazards assumption.

SPHERE Summer Science Day in Tours
On Thursday 29 June, all SPHERE members met in Tours!
The programme included a workshop on the CARER systematic review project and a workshop on the ecological and social transition.
After a convivial lunch that was the occasion of a few photos and a meeting of young researchers, the unit exchanged on how to evaluate the future of patients after reanimation and how to involve patients and caregivers in conducting research.

SPHERE young researchers' days - March 2023
On March 27, 2023, the young researchers of SPHERE met in Nantes for their first scientific day!
On the agenda: presentation of software for the writing of the thesis manuscript and thoughts concerning the group's identity.
We started by a presentation of the LaTeX language and a feedback from former SPHERE PhD students: how did they write their manuscript? What challenges did they face ? etc.
After a convivial moment during lunch, everyone got to work:
- The first group made its first steps with Overleaf, an online Latex editor. This workshop was organized by Floriane and Yseulys.
- The second group worked on the identity of the "young researchers of SPHERE" group, which brings together a wide variety of profiles: interns, residents, PhD students, young doctors, junior engineers, postdoctoral researchers and graduate assistants. They also brainstormed on the actions we could take to stimulate scientific life, cohesion and mutual aid between young researchers.
It is already time to leave, but everyone leaves full of ideas! We will meet again in June at the SPHERE scientific day !

Summer School of Psychometrics 2023
Myriam Blanchin, Yseulys Dubuis, Jean-Benoit Hardouin, Véronique Sébille
The UMR INSERM 1246 SPHERE is organizing its first psychometrics summer school from June 14 to 16, 2023 in Nantes. The theme of the summer school will be "The construction and validation of scales for measuring self-reported outcomes in health".
INSERM workshop 274 "Cluster randomized trials and within-person randomized trials: statistical, practical and ethical issues"
Agnès CAILLE, Bruno GIRAUDEAU (SPHERE) et Laurent BILLOT (The George Institute for Global Health, Newtown, AUS) are organising an Inserm workshop on cluster randomised trials.
The theoretical phase will take place on 21-23 June 2023 in Bordeaux with many international experts.
Practical workshops are proposed in October 2023 in Tours.
Date limite d'inscription : 10 mars 2023

Arthur Chatton and Marion Kerioui received the 2022 Daniel Schwartz award for their thesis !
The 2020-2022 thesis prize «Daniel Schwartz», founder of the French Society of Biometrics, French component of the International Biometric Society (IBS), was awarded to two spherian doctoral students: Arthur CHATTON and Marion KERIOUI
They were invited to present their research at the Journée Jeunes Chercheur.e.s of the Société Française de Biométrie, held in Rennes on 19 January 2023.
Congratulations to both of you!