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Janis Fiedler

@fiejanis.bsky.social
1.1K followers 490 following 117 posts

PostDoc @KIT | wearable technology and mHealth Behavior Change | Exercise Physiology | enthusiastic R amateur | Views are my own orcid.org/0000-0002-9291-2191

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Reposted by Janis Fiedler
Wearable Landscape @wearable-landscape.bsky.social · 26/02/2026
#LivingReview Update ✨ We’ve submitted our Living Review on #wearables #validation studies (2022–2024) to a special issue of the @jmpbjournal.bsky.social! Huge thanks to all co-authors — and special thanks to @fiejanis.bsky.social for the lead👏 🔄 Kick-off for the 2025 update already happened today
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JMIR Publications @jmirpub.bsky.social · 15/12/2025
New in JMIR mhealth: A Refined #Mobile #Health Intervention (SMARTFAMILY2.0) to Promote #PhysicalActivity and Healthy Eating in a Family Setting: Randomized Controlled Trial
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A Refined #Mobile #Health Intervention (SMARTFAMILY2.0) to Promote #PhysicalActivity and Healthy Eating in a Family Setting: Randomized Controlled Trial
Background: Many #Mobile #Health (#mHealth) apps focus on promoting #PhysicalActivity (PA) and healthy eating (HE). However, there is limited empirical evidence regarding their effectiveness in initiating and sustaining behavior change, particularly among children and adolescents. Considering that behavior is influenced by social contexts, it is essential to take core settings like family dynamics into account when designing #mHealth apps. Objective: The purpose of this study was to further develop and refine the SMARTFAMILY (SF) #App targeting PA and HE in a collective family-based setting by enhancing design and usability, as well as by adding gamification aspects, #Health literacy, and just-in-time adaptive interventions to the first version of the #App. Methods: The SF2.0 #App, based on behavior change theories and techniques, was developed, implemented, and evaluated. The #App was used in a collective family setting, with family members using it individually and cooperatively. In a cluster-randomized controlled trial, the intervention group (IG) used the #App for 3 consecutive weeks, while the control group (CG) received no treatment. Primary outcomes included PA measured through self-reports and accelerometry, as well as self-reported fruit and vegetable intake (FVI) for HE. Secondary outcomes included intrinsic motivation, behavior-specific self-efficacy, and the Family #Health Climate. A follow-up assessment (T2) was conducted 4 weeks after the postmeasurement (T1) to assess intervention effects. Multilevel analyses were performed in R (R Foundation for Statistical Computing), considering the hierarchical structure of individuals (level 1) within families (level 2). Results: Overall, 55 families (28 CG, 105/209; 27 IG, 104/209 participants) were recruited for the study. In total, 3 families (3 CG, n=12) chose to drop out of the study due to personal reasons before T0. Overall, no evidence for meaningful and statistically significant increases in PA was observed in favor of the IG of our physically active sample. However, the #App elucidated positive effects in favor of the IG for FVI diary (T0-T1; P=.03), joint PA (T0-T1; P=.02 and T0-T2; P
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Janis Fiedler @fiejanis.bsky.social · 16/12/2025
🧪 Publication alert! Results of the SMARTFAMILY2.0 #mHealth study show: - no effect on physical activity in already active families - increase fruit & veggie intake, joint family activities, and shared meals. OA: doi.org/10.2196/65558 #DigitalHealth #FamilyHealth #BehaviorChange #RCT
This picture shows a family of four around a smartphone with a screenshot of the SMARTFAMILY App.
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Reposted by Janis Fiedler
Wearable Landscape @wearable-landscape.bsky.social · 01/12/2025
#Conference Time Last week our members Marco Giugiu, @fiejanis.bsky.social and @irinatimm.bsky.social presented our Wearable Landscape initiative at the International Symposium on Physical Behaviors 🏋️, Wearable Sensing ⌚️, and Health Analytics 🩺. Thanks to @tu-dortmund.de for hosting this event.
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Nicola Rennie @nrennie.bsky.social · 26/11/2025
One of the things that has been on my to do list for a very long time, is building a gallery of all of the charts I've made across #TidyTuesday, #30DayChartChallenge, #30DayMapChallenge, and other miscellaneous projects 📊 And it's finally here! Link: nrennie.rbind.io/viz-gallery/ #DataViz #RStats
nrennie.rbind.io
Data Visualisation Gallery
Gallery of data visualisations created by Nicola Rennie.
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Cameron Patrick @cameronpat.bsky.social · 25/11/2025
this is one of my favourite observations about sample size calculations. (afaik first articulated by Miettinen in 1985)
"On the first, and pivotal, level the decision is a binary one—the
choice between zero and nonzero as the size. Validity considerations alone are often sufficient to imply that zero is the optimal size"

- O. S. Miettinen "Theoretical Epidemiology" (1985)
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Mario Sixtus @sixtus.net · 24/11/2025
"Schaut man rein auf die Korrektheit der Antworten, beinhaltet ChatGPT zu 51,5 Prozent, Copilot zu 45,4 Prozent, Gemini zu 50 Prozent und Perplexity zu 45,7 Prozent wesentliche Fehler oder Ungenauigkeiten." www.tagesschau.de/wirtschaft/d...
tagesschau.de
Warum Künstliche Intelligenz nicht als Suchmaschine taugt
Die Hälfte der Deutschen verwendet mittlerweile ChatGPT & Co. als Google-Ersatz. Gleichzeitig arbeiten auch die klassischen Suchmaschinen immer mehr mit KI. Warum das ein Problem ist. Von Till Bücker.
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Wearable Landscape @wearable-landscape.bsky.social · 20/10/2025
#MemberMonday Insights from last week’s Wearable Landscape meeting: a big thanks to our core members and supporting students for weekly developing the initiative — and (of course) having some fun along the way :) Let’s keep building our living network! 🌍💡 #Wearables #OpenScience #Collaboration
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Stephan Winter @stephanwinter.bsky.social · 25/09/2025
Exciting new job in Landau 🤩 We’re searching for a Professor of Political Psychology (W2). Very much looking forward to your applications – if you have any questions, please reach out to me. jobs.rptu.de/jobposting/3...
jobs.rptu.de
W 2-Professur für Politische Psychologie (m/w/d)
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Janis Fiedler @fiejanis.bsky.social · 26/09/2025
Can someone help me to find the full text of this? doi.org/10.1080/1074... I checked all my available ressources plus messaged the authors and need it for a systematic review. @academic-chatter.bsky.social @healthpsychology.bsky.social #behSci #SportScience #AcademicSky 🧪
doi.org
Measurement properties of activity monitoring for a rehabilitation (AMoR) platform in post-stroke individuals in a simulated home environment
The aim of this study was to evaluate the measurement properties of activity monitoring for a rehabilitation (AMoR) platform for step counting, time spent in sedentary behavior, and postural change...
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Reposted by Janis Fiedler
Dr. Irina Timm @irinatimm.bsky.social · 02/08/2025
🎓I'm thrilled to share that I've successfully defended my doctoral dissertation on July 25, 25. I want to extend my heartfelt gratitude to my esteemed supervisors, Dr. Marco Giurgiu & Prof. Markus Reichert & Prof. Uli Ebner-Priemer, for their invaluable guidance and support 🙏 @mhealthlab.bsky.social
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Dr. Laura M. König @lauramkoenig.bsky.social · 03/07/2025
#OpenScience principles help students gain lots of useful skills that are an advantage on the job market in and beyond academia. Read our latest book chapter where we provide tips for educators to bolster employability through open science: doi.org/10.31219/osf...
Open science contributes to more rigorous and impactful science. However, little attention is often paid to the benefits that it provides to its users, such as project management and programming skills. Although not its primary objective, these skills may be considered additional benefits supporting the transition to open science practices. Drawing from international perspectives, this chapter will discuss skills that students develop explicitly or implicitly by engaging in open science and their benefits to careers within and outside of academia. It will also showcase examples of how engagement in open science is considered in (academic) hiring decisions, including ongoing debates and areas for (structural) improvement. Ultimately, this chapter will inform educators about the most important open science skills and provide insights into how to strategically build a resume to present open science-related skills convincingly to improve employability, including practical tips and resources.
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Janis Fiedler @fiejanis.bsky.social · 23/06/2025
📊 New Publication! We analyzed 5000+ cycle ergometer tests (ages 14-64) to create reference standards of lactate thresholds for health studies and clinical practice. Full text: doi.org/10.1080/0264... #Exercise #SportsScience 🧪
Displayed are the centile curves at different percentiles for relative and absolute power at the individual lactate threshold.
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Wearable Landscape @wearable-landscape.bsky.social · 02/06/2025
#MemberMonday Recap The past seven weeks introduced each member of our Management Group. A huge thank you to Marco Giurgiu, @fiejanis.bsky.social, @irinatimm.bsky.social, Simon Woll, Til Becker, Doreen Wohlfahrt and @clendt.bsky.social for your contribution to Wearable Landscape! #academicsky 🧪
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Claas Lendt @clendt.bsky.social · 26/05/2025
Happy to be on board! Go check out @wearable-landscape.bsky.social if you haven’t already!
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Janis Fiedler @fiejanis.bsky.social · 26/05/2025
Manchmal ist es wirklich schwierig die Lehre zu füllen.
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Wearable Landscape @wearable-landscape.bsky.social · 19/05/2025
#MemberMonday Doreen Wohlfarth is a research assistant at @kit.edu . She is involved in various projects at the Sports Institute, with her current focus on the Wearable Landscape project. Here she supports our Living Review and other important publications. #SportScience #BehSci #AcademicSky 🧪
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Janis Fiedler @fiejanis.bsky.social · 16/05/2025
I need help. My day only has 1 meeting, and all emails are done. How does this research thing work again? 🧪 #AcademicSky
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Julia M. Rohrer @dingdingpeng.the100.ci · 11/05/2025
Thanks to everybody who chimed in! I arrived at the conclusion that (1) there's a lot of interesting stuff about interactions and (2) the figure I was looking for does not exist. So, I made it myself! Here's a simple illustration of how to control for confounding in interactions:>
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Wearable Landscape @wearable-landscape.bsky.social · 12/05/2025
#MemberMonday Til Becker is a student assistant researcher at the Karlsruhe Institute of Technology ( @kit.edu ) during his master's degree. He sees the Wearable Landscape as great opportunity to improve his own competences and the field of wearables. #SportScience #BehSci #AcademicSky 🧪
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
🌱 This project is 100% non-commercial & driven by passion. We believe science should be accessible, connected & efficient. If you're working on, or interested in, wearable validation—follow along & join us!
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
💡 There is even more: We’re building a collaborative space for the scientific community to... ...share validation protocols ...coordinate studies ...pool equipment ...analyze data together Let’s reduce redundancy & work smarter. #ResearchNetwork #OpenScience
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Wearable Landscape @wearable-landscape.bsky.social · 07/05/2025
🔍 What is Wearable Landscape? An open-science project aiming to foster collaboration in the field of #Wearables. We want to bring experts together, to ultimately advance the validation and application in wearables that track 24-hour physical behavior (sleep, sedentary time, activity) #OpenScience
wearable-landscape.info
Wearable Landscape - Wearable Landscape
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Janis Fiedler @fiejanis.bsky.social · 29/04/2025
My first last-authorship publication is now online! We combined 2 nationwide data sets and found physical exercise and non-smoking to be the most important correlates of aerobic fitness in 14-64. Led by the great Maximiliane Thron #AcademicSky #SportScience #BehSci 🧪 dx.doi.org/10.1002/ejsc...
dx.doi.org
Correlates of Aerobic Performance in Adolescents and Adults
Cardiorespiratory fitness (CRF) is considered as a main indicator of cardiovascular health and is associated with a reduced risk of noncommunicable diseases. The objective is to explore the potential...
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Reposted by Janis Fiedler
Amrei Bahr @amreibahr.bsky.social · 22/04/2025
In der Promotion fand ich Schreiben oft quälend, hab mit jeder Formulierung gekämpft & gehadert. Das hat sich inzwischen zum Glück verändert — v.a. durch Schreibkollaborationen, die das Zutrauen in mein Schreiben gestärkt haben, & durch Routine. Was ich daraus gelernt hab: Heute in #ArbeitInDerWiss!
arbeitinderwissenschaft.substack.com
Weiter im Text: Vom Schreiben inner- und außerhalb der Wissenschaft
Der beste Text ist einer, der gut genug ist, um fertig zu sein.
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Janis Fiedler @fiejanis.bsky.social · 22/04/2025
The joy of post-holiday email dschungle. Do you start with the newest or the oldest ones? 🧪 #AcademicSky
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Wearable Landscape @wearable-landscape.bsky.social · 21/04/2025
New week, new #MemberMonday Dr. Janis Fiedler ( @fiejanis.bsky.social ) is a post-doctoral researcher @kit.edu . His main research interests include #mhealth interventions, and #ExercisePhysiology. He is dedicated to foster an open science culture for the validation of wearables.
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Wearable Landscape @wearable-landscape.bsky.social · 14/04/2025
Welcome Marco to our first #MemberMonday introducing our team: Dr. Marco Giurgiu is a postdoc @kit.edu and focuses his research on the relationship between 24-h #PhysicalBehavior and #Health. He initated and leads our initiative with the vision of a global network to address challenges together.
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ISBNPA @isbnpa.bsky.social · 28/03/2025
Missed the #ISBNPA Systems Science SIG #Webinar "An introduction to systems approaches in public health – where are we up to and how are they being used?" Now’s your chance to catch up! 🎬 Watch the recording here: isbnpa.org/sig/march-24...
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Peter Tennant @pwgtennant.bsky.social · 26/03/2025
The problem with working on big high-risk projects is they don't always end in the glorious impactful work. If they're truly 'high risk', they often just end in failure. Or else requiring huge effort to save. I'm painfully learning this lesson after seeing a few of my 'flagship' projects crash. 🧵
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Janis Fiedler @fiejanis.bsky.social · 26/03/2025
Do you use wearables or plan to implement them in your research? Then check out the @wearemntn.bsky.social ! #digitalhealth 🧪 #Wearables #SportScience
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Wearable Landscape @wearable-landscape.bsky.social · 07/03/2025
🗺️Discover more details on our website and have a look at our #LivingReview.
wearable-landscape.info
Wearable Landscape - Wearable Landscape
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Dr. Christian Scharun @christianscharun.de · 23/03/2025
Wissenschaftliche Artikel hinter Paywalls und wir haben keinen Zugriff? Ein ziemlicher Skandal, denn schließlich haben wir für diese Forschung ja mit unseren Steuergeldern bezahlt! Bei MAITHINK X decken wir heute auf, wie milliardenschwere Verlage die Wissenschaft im Würgegriff haben! Schaut rein! 🧐
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Steuerskandal: Wissenschaft hinter Paywalls
Wissenschaftliche Artikel hinter Paywalls und milliardenschwere Verlage profitieren. Bei MAITHINK X zeigt Mai Thi Nguyen-Kim, was man noch tun kann.
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Prof Andy Field @profandyfield.com · 21/03/2025
Author copy arrived yesterday. It really was a joy working with @ejwagenmakers.bsky.social and Johnny (is he on here?) on this @jaspstats.bsky.social version of the book.
A photo of the textbook 'Discovering statsitics using JASP' on a desk./ The cover has the name in large letters and a drawn image of a futuristic female statuistics professor wearing blue clothes with a circuit-board style print on.
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Janis Fiedler @fiejanis.bsky.social · 14/03/2025
Recent experiences with peer review indicate that either I am really good at writing next to flawless papers OR mmh nah let's not go down that road... #academicsky
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Eiko Fried @eikofried.bsky.social · 12/03/2025
Are you doing EMA research and wonder how to go about it? In recent work we've adressed some open questions and challenges, here is a brief summary of papers and materials. 🧵 #PsychSciSky 🧪 #StatsSky
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ISBNPA @isbnpa.bsky.social · 10/03/2025
Learn all about the latest activities from the #ISBNPA e & mHealth SIG 👇 isbnpa.org/sig/e-mhealt...
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Janis Fiedler @fiejanis.bsky.social · 06/03/2025
Would be great if anyone could help finding it for our systematic review! Else I'd have to leave it out.
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Janis Fiedler @fiejanis.bsky.social · 05/03/2025
Need your help! 🧪 #AcademicSky Does anyone have access to: Zhang et al., (2019). The acute effects of a 25-min afternoon physical activity class on attentional performance in Chinese elementary school children. International Journal of Sport Psychology, 50(1), 26-37. doi:10.7352/IJSP.2019.50.026
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Janis Fiedler @fiejanis.bsky.social · 24/02/2025
We are updating our living review regarding validation studies of #wearables for the years 2022-2024. Current state TIAB Screening of the 8.011 studies Want to be up to date? Check our website: www.wearable-landscape.info and follow us: @wearable-landscape.bsky.social 🧪 #SportScience #BehSci
wearable-landscape.info
Wearable Landscape - Wearable Landscape
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Simon P. Couch @simonpcouch.com · 20/02/2025
New #rstats pkg gander is now on CRAN! gander is a coding assistant that knows how describe the objects in your global R environment. So, when you're working with data, LLMs will know the names, types, and distributions of data columns, resulting in much more effective completions.
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Dr Suzanne McDonald @suzannemcdonald.bsky.social · 14/02/2025
Pleased to see this paper just published. We explore the need for personalised research methods (including #Nof1 methods) in psychology. Traditional methods often fall short because they assume what works for the ‘average’ person works for everyone -rarely true! journals.sagepub.com/doi/10.1177/...
Personality psychology is getting personal: Advancing the field through personalisation.
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Eiko Fried @eikofried.bsky.social · 13/02/2025
1/3 Tutorial on exploring ecological momentary assessment data is online at AMPPS, with: - Accessible ways to visualize data for better understanding - Models to get some first insights - Further reading boxes for more advanced topics - Reproducible pipeline you can run over your own data
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Prof. Emily Nordmann @emilynordmann.bsky.social · 11/02/2025
You there! Would you like to learn how to make very pretty graphs in #rstats? I'm delivering a short introduction to data viz in R on 15th April. Online, free (I think), and no prior knowledge or experience of R required. #AcademicSky www.apa.org/education-ca...
apa.org
Data visualization in R for researchers who do not use R
Learn the basics of data visualization in R using ggplot and how to make boxplots, histograms, violin-plots, bar charts, and scatterplots.
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UCL Centre for Behaviour Change @ucl-cbc.bsky.social · 11/02/2025
Registration is open for #LYP2025, a day of connections, insights & action focused on accelerating the green transition in the UK. Join UCL faculty, including our Director @susanmichie.bsky.social, policy influencers, industry leaders & civil society advocates. 🔗 www.eventbrite.co.uk/e/love-your-...
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EHPS Synergy @ehpssynergy.bsky.social · 04/02/2025
Last chance to join the EHPS Synergy Winter School 2025 on mixed and multilevel models! The deadline for applications is extended to Friday 7th February 2025, 23:59 GMT Click here for more info and to apply: lnkd.in/eKN63fN2 @ehps.bsky.social @ehpscreaters.bsky.social @empowerehps.bsky.social
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Professor Clare Collins AO @profccollins.bsky.social · 03/02/2025
Do #detox and diet #cleanses work? We discuss this #nutritionsciencebites + the body's detoxification processes, misconceptions, potential risks and how detox promises may not align with what the science says! @nmnteatwell.bsky.social Listen on Apple shorturl.at/hlaC9 or Spotify shorturl.at/cESOK
shorturl.at
Do detox and diet cleanses work?
Podcast Episode · Nutrition Science Bites with Professor Clare Collins AO · 03/02/2025 · 16m
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Rushani Wijesuriya @rush-099.bsky.social · 27/01/2025
Hot off the press! 📣📣In this tutorial we illustrate available multiple imputation approaches for handling longitudinal data including when they are clustered within higher level clusters. A reproducible example with R and Stata code provided! #OpenAccess onlinelibrary.wiley.com/doi/10.1002/...
onlinelibrary.wiley.com
Multiple Imputation for Longitudinal Data: A Tutorial
Longitudinal studies are frequently used in medical research and involve collecting repeated measures on individuals over time. Observations from the same individual are invariably correlated and thu....
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Peter Stefanovic @peterstefanovic.bsky.social · 24/01/2025
Bluesky’s science takeover: 70% of Nature poll respondents use platform Roughly 6,000 readers answered the poll, with many declaring that Bluesky was nicer, kinder and less antagonistic to science than X 👏 www.nature.com/articles/d41...
nature.com
Bluesky’s science takeover: 70% of Nature poll respondents use platform
Roughly 6,000 readers answered our poll, with many declaring that Bluesky was nicer, kinder and less antagonistic to science than X.
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Janis Fiedler @fiejanis.bsky.social · 26/01/2025
The second day of the Workshop on Multilevel Models of the #asp is starting! Yesterday, we learned about linear models and the importance of centering. Today, we will explore fixed and random effects, along with ICC, BIC, and AIC. Excited for the day and grateful for participants' engagement! #R 🧪
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