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Frank Harrell Profile
Frank Harrell

@f2harrell

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Biostatistician/Professor/Founding Chair of Biostatistics, Vanderbilt U. Blog: Statistical Thinking: @f2harrell on

Nashville, TN
Joined January 2017
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@f2harrell
Frank Harrell
2 years
We lost one of the greatest statisticians of all time: Sir David Cox, developer of both the binary logistic regression model (1958) and the Cox proportional hazards model (1972), but so much more. @vandy_biostat #Statistics #biostat
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@f2harrell
Frank Harrell
5 years
My close colleague Sam Nwosu @vandy_biostat flabbergasted me today with the gift of a batch of biostatistics cookies made by his wife Brionni, including a cookie version of my book! Much easier to digest than the paper version ...
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@f2harrell
Frank Harrell
2 years
Announcing that my free text Biostatistics for Biomedical Research has been significantly updated and turned into a 22 chapter reproducible e-book thanks to @rstudio 's Quarto : #bbrcourse #Statistics #clinicaltrials #RStats @vandy_biostat @EdgeforScholars
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@f2harrell
Frank Harrell
4 years
100 pages of online course notes added for Regression Modeling Strategies: intro to survival analysis and parametric survival models: now 504 pages #bbrcoourse #Statistics @vandy_biostat
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@f2harrell
Frank Harrell
2 years
What an 11 days. Positive stress echo test on July 15, cardiac cath on 19th, coronary bypass surgery on 20th, home 24th. Incredible medical care from cardiologist Dr See, surgeon Dr Shah, teams @VUMChealth , support and care from my md wife Liana & family/friends/colleagues.
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@f2harrell
Frank Harrell
5 years
Toying with the idea of hosting an almost-weekly one-hour live webinar (with student participation) on applied statistics/biostatistics. Some topic choices would come from twitter polls. Please respond to the poll in the next tweet if you are definitely interested.
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@f2harrell
Frank Harrell
6 years
Statistical thought of the day: bad statistical practice is so pervasive in so much of observational research that correlation is not correlation.
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@f2harrell
Frank Harrell
2 years
This t-shirt says it all
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@f2harrell
Frank Harrell
2 years
Charlotte Briggs Harrell 1926-2021 Today I lost my dear mom, two weeks after her 95th birthday. I feel a great emptiness but I also feel wonder at how could I have been this lucky to have had her as a mom.
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@f2harrell
Frank Harrell
4 years
#rstats discovery of the day: patchwork: elegant grammar for combining plots: by @thomasp85
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@f2harrell
Frank Harrell
2 years
R Workflow is now an e-book at - it's a result of 31 years of using R & its precursor S in reproducible biomedical research, and capitalizes on Quarto, data.table, ggplot2, Hmisc,... #Rstats @vandy_biostat @VUDataScience #DataScience #Statistics @rstudio
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@f2harrell
Frank Harrell
2 years
Regression Modeling Strategies course notes have been significantly expanded, updated, and converted into a free #quarto e-book at #rmscourse @vandy_biostat @VUDataScience #RStats @quarto_pub @EdgeforScholars #Statistics
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@f2harrell
Frank Harrell
5 years
Galben Harrell - one of the saddest days of my life to lose him to Cushing's disease today. He was about 12 years old. A finer friend and companion I could not imagine.
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@f2harrell
Frank Harrell
4 years
New R package rmsb: Bayesian counterpart to the rms (regression modeling strategies) package now on CRAN. Uses pre-compiled @mcmc_stan code. Information including lots of examples at #rmscourse @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
5 years
Clinicians: please give me hope as a teacher by telling me that you understand that NNT does not apply to an individual patient unless the average baseline risk in the data used to compute NNT just happened to equal the baseline risk of the individual.
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@f2harrell
Frank Harrell
6 years
Most straightforward definition of p-value I've been able to write: the probability that someone else's data are more extreme than mine if their data were generated with my H0 in effect. p-values tell nothing more than that.
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@f2harrell
Frank Harrell
6 years
Announcing - a place for discussions about data-related methods where methodologists meet clinical, translational, health researchers to discuss design, analysis, measurement, interpretation, articles, and more. Rationale@
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@f2harrell
Frank Harrell
5 years
#Statistics thought of the day: Seek probability of a real difference given data, not prob. of data given no real difference. Be bold. Embrace Bayes. Embrace transparent criticizable use of prior beliefs & operate in a predictive actionable mode.
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@f2harrell
Frank Harrell
6 years
Biostatistics for Biomedical Research - 472 pages developed from collaborations with basic+clinical researchers. All my teaching materials not related to predictive modeling or Bayes. Clinicians: let me know what needs to be added. [source on Github]
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@f2harrell
Frank Harrell
5 years
Seeing the surgeon authors call us "trolls" reminds me of this: Apparently surgeons can practice statistics with zero training, but were I to practice surgery I would be arrested.
@boback
Boback Ziaeian 🤦🏻‍♂️
5 years
Statisticians clamor for retraction of paper by Harvard researchers they say uses a “nonsense statistic” ⁦ @ADAlthousePhD ⁩ ⁦ @RetractionWatch
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@f2harrell
Frank Harrell
5 years
Forget deep learning. We need to study deep stupidity.
@CBSNews
CBS News
5 years
Hundreds rally to preserve right not to vaccinate children amid measles outbreak
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@f2harrell
Frank Harrell
3 years
#Statistics thought of the day: #MachineLearning is not so much for high dimensional data but for data where interrelationships among predictors and outcome are too complex to model with a statistical model that assumes additivity by default. @VUDataScience #rmscourse
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@f2harrell
Frank Harrell
5 years
Biostatistics for Biomedical Research almost-weekly web course registration is now open. Go to for course details and registration link. @EdgeforScholars #bbrcourse @vandy_biostat @VUMChealth #StatThink
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@f2harrell
Frank Harrell
4 years
#Statistics thought of the day: If I voiced as many clinical opinions as some clinicians voice statistical opinions I'd be in hot water.
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@f2harrell
Frank Harrell
1 year
1/2 @drjohnm has a wonderful piercing commentary about an incredibly harmful paper published in @CircAHA . The paper's authors use of the phrase "real world" is repugnant. (A problem w/ substack: can't add comments there unless you pay). @EdgeforScholars
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@f2harrell
Frank Harrell
4 years
The ethics of not randomizing convalescent plasma needs serious consideration. The negative consequences on public health and science are potentially huge.
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@f2harrell
Frank Harrell
6 years
Idea for replacing our nearly broken journal and peer review systems: academics create their own electronic journals/archives, peer reviews are open and authored, and work with universities to give credit for peer review equivalent to (1/k) × writing a paper, for suitable k.
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@f2harrell
Frank Harrell
5 years
How to convince me of a subgroup effect: (1) don't do "subgroup analysis"; use model-based estimates on the whole sample; (2) show strong evidence for a pre-specified interaction adjusted for all main effects; (3) demonstrate smooth dose-response effect of interacting factor.
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@f2harrell
Frank Harrell
5 years
Glossary of statistical terms, especially for non-statisticians: datamethods has the link and provides a place to suggest improvements or define new terms:
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@f2harrell
Frank Harrell
6 years
Statistical graphics resource suggestion of the day: I just stumbled upon the online #rstats plotly book. Terrific methods for graph construction, use of html widgets, linking graphs, and more: . Highly recommend plotly graphics model for html reports.
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@f2harrell
Frank Harrell
1 year
The R Hmisc package, started in 1991, just underwent the biggest update in its history with version 5, now on CRAN. Many new functions and no longer loads other packages at startup: #rstats @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
3 months
For researchers using the wonderful REDCap electronic data capture/research data management system, Chapter 5 of has new sections on automatic interfaces between REDCap and R. #rstats
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@f2harrell
Frank Harrell
4 years
Soon to release version 6.0 of the R rms package(a 29 year project). With much help from @mcmc_stan guru Ben Goodrich now has blrm for Bayesian binary/ordinal logistic models w/ random effects. Nomograms and other model graphics. Bayes is getting easier:
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@f2harrell
Frank Harrell
4 years
Our checklist for authors for statistical issues in study design, analysis, and reporting has been updated and has a new home on datamethods. It is a wiki so that others can improve the content, in addition to posting suggestions as replies. #bbrcourse
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@f2harrell
Frank Harrell
4 years
Starting with a job as a research aide as an 18 year old, I'm celebrating my 50th consecutive year working in cardiology. What a great field in which to collaborate, with great researchers! #cardiotwitter #Cardio #Cardiovascular @califf001 @DanMarkMD @boback @CMichaelGibson
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@f2harrell
Frank Harrell
2 years
If @CDCgov is trying to gain back credibility they won't do it with crappy research like this @vandy_biostat @EdgeforScholars #COVID19
@VPrasadMDMPH
Vinay Prasad MD MPH
2 years
A few thoughts on the CDC's newest "science" 👇👇👇
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@f2harrell
Frank Harrell
5 years
Language to use to get favorable peer review in #medicine : We will use AI to describe heterogeneity of treatment effect, leading to #PrecisionMedicine and optimizing the number needed to treat, while making startling discoveries about pt's microbiome effects on medical decisions.
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@f2harrell
Frank Harrell
8 months
Best book advertisement I could get. Thanks @ChelseaParlett and use to see several new case studies. has several simpler case studies. #rmscourse #bbrcourse
@ChelseaParlett
Chelsea Parlett-Pelleriti
8 months
@topepos @rlmcelreath 📕Regression Modeling Strategies @f2harrell is the G.O.A.T. This book is like an encyclopedia for all the regression models you’re dying to use in your work. From ordinal models, to survival analysis…this book has it all. And endless case studies to see them in action.
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@f2harrell
Frank Harrell
5 years
Vaccine denier: one who has an understanding of benefits vs. risks that is so poor that when he is offered a parachute in a plane about to crash he declines the parachute because of an allergy to nylon.
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@f2harrell
Frank Harrell
5 years
Nice piece. Lack of proper normalization is the tip of the "avoiding #Statistics " iceberg: Forbes: How Data Scientists Turned Against Statistics. via @GoogleNews
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@f2harrell
Frank Harrell
6 years
It's easy to create a statistical checklist of what NOT to do - we've had this for years:
@StatModeling
Andrew Gelman et al.
6 years
The statistical checklist: Could there be a list of guidelines to help analysts do better work?
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@f2harrell
Frank Harrell
6 years
Still believe in p-values? If so, you need to know exactly what you're getting:
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@f2harrell
Frank Harrell
4 years
New major release of R rms package coming soon. Includes Bayesian Stan-based binary and ordinal logistic regression allowing for the rms capabilities such as partial effect plots, nomograms, etc. Examples here: #rstats @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
3 years
The #RStats Hmisc package on CRAN is 30 years old and still getting a lot of enhancements and bug fixes. @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
5 years
Biostatistics for Biomedical Research web course is likely to start Sept 27. Voting for time of day is too close to call at present. First session will cover Chapter 3 of up to Random Variables.
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@f2harrell
Frank Harrell
6 years
Optimum decision making in presence of uncertainty comes from probabilistic thinking. The relevant probs. are of a predictive nature: P(the unknown | the known). Thresholds are not helpful and are completely dependent on the utility/cost/loss function.
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@f2harrell
Frank Harrell
5 years
Honored to be presenting thoughts on machine learning vs. statistical modeling in health research at @JohnsHopkinsSPH @jhubiostat Johns Hopkins' esteemed Dept. of Biostatistics on Monday. The talk has something to offend everyone:
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@f2harrell
Frank Harrell
3 years
#Statistics thought of the day: Of all the statistical assumptions that are routinely violated that matter the most, the linearity assumption is near the top of the list @vandy_biostat @VUDataScience #rmscourse @EdgeforScholars #bbrcourse
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@f2harrell
Frank Harrell
4 years
#Statistics thought of the day: #MachineLearning is to statistical models as #PrecisionMedicine (including biomarker-guided therapy and PRS) is to using standard clinical information. Neither ML nor precision med is living up to its hype.
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@f2harrell
Frank Harrell
6 years
New blog article to help in the choice between developing statistical models and #Machine_Learning algorithms (especially in #medicine ):
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@f2harrell
Frank Harrell
2 years
Big update to R Workflow includes Consort and Mermaid diagrams, analyzing data about the data, missing data patterns, descriptive graphics for discrete & continuous longitudinal data & time-to-event data. #RStats @vandy_biostat @VUDataScience @rstudio
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@f2harrell
Frank Harrell
5 years
Best advice for drawing an ROC curve: use invisible ink. The visibility would then match its utility.
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@f2harrell
Frank Harrell
3 years
#Statistics thought of the day: to relax the linearity assumption in regression, don't categorize continuous variables. Use cubic splines, which only categorize the 3rd derivative (jolt) of Y vs X #rmscourse #bbrcourse @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
4 years
Garbage in, garbage out:
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@f2harrell
Frank Harrell
1 year
The #RStats Hmisc package has another major update. One of the biggest changes is new output options for describe() including interactive sparklines for spike histograms. @vandy_biostat
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@f2harrell
Frank Harrell
5 years
Surprising fact of the day for clinicians: often treatment efficacy estimates from narrowly focused RCTs are more relevant to clinical practice than "real world" estimates from diverse populations, because of systematic bias in the latter.
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@f2harrell
Frank Harrell
3 years
#Statistics thought of the day: Witnessing the continued hype of #AI by academic medicine and industry makes me think that we should spend more time on #RHI (Real Human Intelligence). @vandy_biostat @VUDataScience #StatThink @MaartenvSmeden
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@f2harrell
Frank Harrell
5 years
Are you a fan of point null hypothesis testing in medical research? Save a lot of time and money---unless you are studying homeopathy, most dietary supplements, or acupuncture, you can safely assume all null hypotheses are false.
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@f2harrell
Frank Harrell
4 years
#Statistics #clinicaltrial thought of the day: a randomized trial on a patient sample differing much from the target population provides a much better estimate of effectiveness for the target pop. than an observational study done ON the target pop.
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@f2harrell
Frank Harrell
3 years
Wonderful Mother's day with younger brother Bill (aka Moose, also a Vandy guy) and inspirational 94 year old mom Charlotte
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@f2harrell
Frank Harrell
6 years
Highly probable statistical fact of the day: the gains in predictive ability in medical research claimed by #MachineLearning that are validated are less than the gains that would be achieved by applying best statistical practice to statistical modeling #StatThink
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@f2harrell
Frank Harrell
2 months
Sometimes I wish we had introduced ordinal variable values as letters of the alphabet so people would not be tempted to use non-interval-scaled ones as numeric. This will be a great presentation by @rlmcelreath . And the R brms package can handle ordinal X and ordinal Y.
@rlmcelreath
Richard McElreath 🦔
2 months
Likert scores are not integers and they cannot be subdued by pretense. Stop pretending and meet me in the warm 3rd circle of stats hell and learn about ordered categorical models. Lecture:
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@f2harrell
Frank Harrell
5 years
Significant update to the R Hmisc package to version 4.2-0. Hmisc is now > 25 years old! Changes are described here: . Many of the changes relate to html report writing and plotly graphics.
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@f2harrell
Frank Harrell
5 years
When two employees are fired for reporting sexual harassment and the alleged harasser is not, the culture and actions of a company are worth a closer look.
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@f2harrell
Frank Harrell
4 years
This is one of the best introductions to Bayesian inference for non-statisticians I've ever seen, plus a great overview of frequentist #Statistics : @jmirpub @marcusbendtsen #bbrcourse #Bayesian
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@f2harrell
Frank Harrell
15 days
#Statistics throught of the day: If sponsors knew how much money was wasted with fixed sample size designs, and how much earlier Bayesian sequential designs would have bailed out on ineffective treatments, they'd be shocked.
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@f2harrell
Frank Harrell
6 years
Extremely important methods comparison: multiple different analyses of the same dataset
@BrianNosek
Brian Nosek (@[email protected])
6 years
Published! "Many Analysts, One Dataset: Making transparent how variations in analytical choices affect results" 65 of us led by Raphael Silberzahn demonstrate the contingencies of analytic decisions on observed outcomes. (OA: )
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@f2harrell
Frank Harrell
6 years
Statistical thought for the day - why classification is seldom what is needed for decision making and why probabilistic thinking is helpful: .
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@f2harrell
Frank Harrell
6 months
For anyone manipulating longitudinal data, the data.table package in #rstats is invaluable. Here is a new example, of regularizing irregularly-timed longitudinal measurements: @vandy_biostat #Statistics #DataScience
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@f2harrell
Frank Harrell
5 years
Nice discussion of how to collapse/reduce a large number of levels in a categorical predictor:
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@f2harrell
Frank Harrell
5 years
Final results are in. Thanks to 1422 voters! Friday mornings 10am US ET works for most people (sorry Australia!) for live stream of free BBR biostatistics course. More details about planning are at #teaching and
@f2harrell
Frank Harrell
5 years
If interested in participating in an almost-weekly 1 hour applied stat/biostat series please respond:
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@f2harrell
Frank Harrell
5 years
The Last Walk - noble friend Galben before going for surgery, complications of which he could not overcome (caught by security cam):
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@f2harrell
Frank Harrell
5 years
Turned off by statistical significance? Afraid that clinical significance cannot be derived from null hypothesis testing? Worried about choice of non-inferiority margins? Bayesian posteriors provide evidence for all possible effect magnitudes:
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@f2harrell
Frank Harrell
4 years
#Statistics thought of the day: If age is a strong prognostic factor, a hazard ratio that doesn't adjust for age is effectively comparing some of the younger patients on treatment A with some of the older patients on treatment B even with perfect covariate balance. #bbrcourse
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@f2harrell
Frank Harrell
14 days
This is a must-see on many levels. While watching it I became frightened at how things are so similar in my field of #Statistics especially related to @skdh 's comment "They just wanted to write papers", plus how fad-driven is #Statistics .
@skdh
Sabine Hossenfelder
15 days
How I fell out of love with academia (this video was an accidental publication/scheduling blunder😬😬 but well uh, happy Friday I guess)
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@f2harrell
Frank Harrell
2 years
#Statistics thought of the day: If you must use any cutpoints for continuous variables, only use them for the 3rd derivative of how the variable relates to outcome, i.e., use cubic splines #statstwitter @vandy_biostat @VUDataScience
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@f2harrell
Frank Harrell
4 years
An honor to have Ellie Murray @EpiEllie visit @vandy_biostat and to be able to attend a great seminar and chat with her, plus to take part in a @casualinfer podcast recording with Ellie and @LucyStats . #epitwitter
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@f2harrell
Frank Harrell
6 years
Statistical quote of the day. Stepwise variable selection has done incredible damage to science. How did we statisticians let this happen?
@mc_hankins
Matthew Hankins
6 years
A journey of a thousand hypotheses begins with a single stepwise regression
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@f2harrell
Frank Harrell
3 years
Relative risk was never a good measure; it's perceived to be interpretable precisely because it is misinterpreted. This excellent paper helps to put the nail in the coffin with data and math. @TChivese @bbrcourse #rmscourse @vandy_biostat
@JClinEpi
Journal of Clinical Epidemiology
3 years
#openaccess Questionable utility of the relative risk in clinical research: A call for change to practice
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@f2harrell
Frank Harrell
3 years
Clinical trialists: A major inefficiency in randomized trials, resulting in inflation of needed sample size, is the belief by investigators in dichotomizing individual patient responses to be in line with how you want to interpret the study. Not needed!
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@f2harrell
Frank Harrell
4 years
Giving a seminar @Stanford @StanfordMed yesterday and having the incomparable Brad Efron in attendance was a deep honor. Not to mention the amazing @HeartBobH (background), Rob Tibshirani, Trevor Hastie, @goodmanmetrics and so many others I revere ... daunting! @vandy_biostat
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@f2harrell
Frank Harrell
5 years
Statistical thought of the day: I don't embrace the Bayesian paradigm because it is without problems. I embrace it because (1) it solves the most problems and (2) null hypothesis significance testing, p-values, and type I error are beyond repair. Mixing Bayes+frequentist=mess.
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@f2harrell
Frank Harrell
12 days
R Workflow online e-book is constantly expanding. Latest updates listed here: (see Update History at the bottom). Latest: advanced tables that work in both html and Word #rstats @vandy_biostat
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@f2harrell
Frank Harrell
4 years
#Statistics question of the day: Why criticize a Bayesian's choice of prior and never question your own choice of the ratio of type II assertion probability to type I assertion probability β/α being set to 4.0? (α=0.05, β=0.2) #Bayes #bbrcourse @vandy_biostat
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@f2harrell
Frank Harrell
1 year
My course notes on Bayesian methods for evaluating treatments have been expanded and reformatted using @quarto_pub : #Statistics #statstwitter #bbrcourse @vandy_biostat #bayesian #clinicaltrials
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@f2harrell
Frank Harrell
6 years
Paper for non-statisticians written in 1988: explaining how to not assume linear effects of predictors of outcomes, using splines and avoiding dichotomania: #StatThink
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@f2harrell
Frank Harrell
3 years
Use #rstats and looking to learn something new? data.table is one of the very best things to learn. New resource page available: @vandy_biostat @VUDataScience #StatThink
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