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Tim Morris

@timpmorris.bsky.social

2.3K followers 450 following 1.4K posts

Biostatistician working on methodology at Novartis. Simulation studies, non-inferiority, missing data, estimands, covariate adjustment… He/him https://tpmorris.substack.com/

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Tim Morris @timpmorris.bsky.social · 4h

New (short) post on hearing criticism of your work.

No, I’m not telling you who it was – they will recognise themself!

open.substack.com/pub/tpmorris...

Reposted by Tim Morris

Darren Dahly @statsepi.bsky.social · May 2

My favorite genre of fiction is Thesis Acknowledgments.

Tim Morris @timpmorris.bsky.social · 14d

Straight onto my reading list

arXiv stat.ME Methodology @statme-bot.bsky.social · Aug 22

Arman Oganisian: Untangling Sample and Population Level Estimands in Bayesian Causal Inference https://arxiv.org/abs/2508.15016 https://arxiv.org/pdf/2508.15016 https://arxiv.org/html/2508.15016

Tim Morris @timpmorris.bsky.social · 23d

The defenders of British Values, having completed their work assaulting police officers, have returned home, leaving London a Dystopian Hellscape once again

The morning sun peeping around some horse chestnuts (non-native) and hornbeams (non-native)

Tim Morris @timpmorris.bsky.social · 23d

Bonus marks for explaining why the quoted post appears to be wrong but the quoting post is in fact wrong.

Tim Morris @timpmorris.bsky.social · 27d

Why does everyone who picks up the mic at this conference feel they have to mention this talk, whether grudgingly or positively??

Tim Morris @timpmorris.bsky.social · 27d

Hahaha I enjoyed that! Yes, I agree on the sentence/s (these documents do not cite any references though, which always annoys people).

Tim Morris @timpmorris.bsky.social · 27d

Very much agree with that last point. I think what you’re politely saying translates to “come back when you’ve read my 🤬 paper!”

Tim Morris @timpmorris.bsky.social · 27d

The second sentence of your abstract!

Tim Morris @timpmorris.bsky.social · 27d

Isn’t this like complaining that the bus to the airport fell short when it didn’t fly you to your destination? 😜

It’s gives us a useful (important) start but is not a grand-unifiying-all-singing-all-dancing solution!

Tim Morris @timpmorris.bsky.social · 27d

😜

Tim Morris @timpmorris.bsky.social · 27d

I’m just a bit baffled about what you think this is “inferior to”. Writing an subsequent expression in terms of potential outcomes? If so, this should come from the natural-language version, not compete with it.
E.g. doi.org/10.1002/sim....

Tim Morris @timpmorris.bsky.social · 27d

Inferior to what? For the Addendum, the whole point is to give a structured description of the estimand in natural-language.

This should *not* set the estimand in stone – we cannot just skip past identification, estimation, implementation &c. – though practice isn’t as good as the intention.

Tim Morris @timpmorris.bsky.social · 27d

Yes, thanks. I disagree with your premise too as I disagree with Hernán’s grift: being able to say what trial you would like to do does not say what the estimand is, it’s something like “the estimand would be identified under this design”. But a causal estimand does not depend on study design!

Tim Morris @timpmorris.bsky.social · 28d

Definitely. I guess lots of useful approaches gain this problem once popular (estimands for one). A superficial label accompanied by no-thinking.

Tim Morris @timpmorris.bsky.social · 28d

Yes, agree!

Tim Morris @timpmorris.bsky.social · 28d

Thanks Cameron!
Dean, two key points:
1. It’s the structure in this pic that we all find so useful.
2. The “Intercurrent event strategies” mean interplay with the other four attributes.

Screenshot of a slide.
Title: “Addendum contributions (‘IMO’)”
Left hand column says
“Five ‘attributes’
1. Treatment condition of interest
2. Target population
3. Outcome variable
4. Intercurrent events
5. Population-level summary
measure”
Right hand column says
“Handling intercurrent events (LHS point 4)
1. ‘Treatment policy’
2. ‘Hypothetical’
3. ‘Composite variable’
4. ‘While on treatment’
5. Principal stratum”

Tim Morris @timpmorris.bsky.social · 28d

One more. In comparing “Trials” & “Target trials”, slide says something like “causal contrasts” vs. “observational analogs of contrasts”. Causal contrasts are of potential outcome distributions (see Hernán & Robins’ book), which do not depend on the study design – no “observational analog”!

Tim Morris @timpmorris.bsky.social · 28d

The target trials concept is great; I’m not slamming that. But even the poster-child examples leave a lot ambiguous (partly because they seem to rely on readers being able to reverse-engineer estimands).

Tim Morris @timpmorris.bsky.social · 28d

I’d say substance was largely absent. Most gripes were about minor semantic things. Seemed like sour grapes that the trials community didn’t think “real trials have target trials too” solved everything for them, and he wants them to turn back from this 🤷

Tim Morris @timpmorris.bsky.social · 28d

Having to infer the estimand from the design + analysis was one of the things that led to the E9(R1) addendum in the first place!
Also that the “ITT effect [sic] is never relevant” thing, avoiding engaging with how you would realise a different intercurrent event strategy in practice.

Tim Morris @timpmorris.bsky.social · 28d

I’ve heard about this second-hand but assumed it was a caricature.
He is claiming that describing a target trial protocol makes the estimand crystal clear, so there is no need for anything else. But if we actually did the target trial, we would have to infer the estimand from design + analysis!

Tim Morris @timpmorris.bsky.social · 28d

Miguel Hernán is presenting at EFSPI and giving a frankly embarrassing rant about (addendum-style) estimands. While lots of people are constructively using it to complement causal inference, he is sticking to basic & straw-man gripes that are easily addressed by thinking or listening to others.

Tim Morris @timpmorris.bsky.social · Sep 5

That’s it. I can see that power dynamics are a problem, and that’s probably why there’s a reluctance to challenge anything from PPI colleagues, but no challenge makes the whole activity… inauthentic, right?

Tim Morris @timpmorris.bsky.social · Sep 5

Sorry to pick on this one sentence. I just thought the question “is it allowed to be negative about PPI” was a very interesting one.
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