Fang Han Profile
Fang Han

@johnleibniz

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@johnleibniz
Fang Han
3 years
Not a junior researcher fighting for the space of the Annals of Statistics any more… but hey, every acceptance still deserves a new “bound”.
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@johnleibniz
Fang Han
3 months
Wow, impressive!!! My morning attempt using martingale theory only...
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@__SimonCoste__
Simon Coste ꙮ
3 months
I only knew one proof of the DKW inequality and it's not easy at all ! Nice achievement
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@johnleibniz
Fang Han
1 month
I put it in my book draft:
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@sp_monte_carlo
Sam Power
1 month
Baller (from )
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@johnleibniz
Fang Han
4 months
My favorite quote of Talagrand (Probability in Banach Spaces, with Ledoux). Talagrand has the magic to turn complex things simple.
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@johnleibniz
Fang Han
4 months
The real challenge in VC type theorems, which is usually hidden in learning theory, is the measurability requirement on the studied objects. This is a long-forsaken bug that one you noticed, is hard to get away from.
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@johnleibniz
Fang Han
8 months
This is a fun collaboration, for which I learnt a lot from two coauthors Peng ( @pengding00 ) and Zhexiao ( @zzzxlin ). A special shout-out to Zhexiao, who just started his 2nd year PhD study (!).
@ecmaEditors
Econometrica
8 months
We revisit the Abadie-Imbens study on nearest neighbor matching and show that, with a diverging number of nearest neighbors, matching estimators can be doubly robust and semiparametrically efficient for estimating the average treatment effect
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@johnleibniz
Fang Han
4 years
Hmmm... 3 AoS papers in one issue; what should I say? congrats to myself 🤪? Random matrix theory: Rank correlation: Variance estimation:
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@johnleibniz
Fang Han
1 year
Rina, Peng ( @pengding00 ), Nicole, and I are organizing an IMSI workshop aimed at forging connections between causal inference, distribution-free methods, and probability theory, within the overarching theme of "permutation".
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@johnleibniz
Fang Han
1 year
The dust finally settles: my students Yandi Shen () & Hongjian Shi () will join the stats departments at 𝗖𝗠𝗨 & 𝗪𝗮𝘁𝗲𝗿𝗹𝗼𝗼 as TT ass profs. They're true scholars and I feel fortunate to have worked with them. #AcademicPride
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@johnleibniz
Fang Han
6 months
If you keep convoluting the same density function but deliberately keep the mean and variance stable, then it will eventually converge to a distribution with the maximum entropy under that mean/variance constraint. CLT is confirming the second law of thermodynamics.
@gabrielpeyre
Gabriel Peyré
6 months
The central limit theorem equivalently reads as the convergence of iterated convolutions.
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@johnleibniz
Fang Han
2 months
This Le Cam-style paper is going to appear in an upcoming issue of 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮. The brilliant first author, Yihui, will join stat @Wharton in the coming year; yes, he is still an undergrad at math @PKU !
@mathSTb
arXiv math.ST Statistics Theory
8 months
Yihui He, Fang Han: On propensity score matching with a diverging number of matches
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@johnleibniz
Fang Han
24 days
This paper is going to appear in a future issue of the Annals of Applied Probability; it gives the limiting distribution of Chatterjee’s correlation when the data are supported over a manifold.
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@johnleibniz
Fang Han
6 months
The paper () now will appear in a future issue of 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮. The message is one-line: Chatterjee's rank correlation is root-n consistent, asymptotically normal, but 𝗶𝗿𝗿𝗲𝗴𝘂𝗹𝗮𝗿, and hence bootstrap inconsistent.
@johnleibniz
Fang Han
1 year
Ok, the literature review is done: Beran (1997) showed that in LAN models, bootstrap consistency is equivalent to that the estimator is regular; should be a textbook result IMHO.
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@johnleibniz
Fang Han
3 years
: Our holiday gift to all fans of matching methods: in strong contrast to the common belief, Abadie and Imbens's bias-corrected nearest neighbor (NN) matching actually already gives a doubly robust and semiparametrically efficient estimator of the ATE.
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@johnleibniz
Fang Han
5 months
This deserves being repeatedly said: Conformal prediction gives marginal instead of conditional coverage, and it rarely works for time series prediction.
@beenwrekt
Ben Recht
5 months
What does conformal prediction actually guarantee? I predict it’s not what you want.
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@johnleibniz
Fang Han
2 years
"On the power of Chatterjee's rank correlation" is currently among 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗿𝗲𝗮𝗱 𝗮𝗿𝘁𝗶𝗰𝗹𝗲𝘀 𝗶𝗻 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮; please take a look if interested in measuring functional dependence, Le Cam's method, or rank/permutation statistics.
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@johnleibniz
Fang Han
2 years
Accepted to 𝗕𝗲𝗿𝗻𝗼𝘂𝗹𝗹𝗶. This is the first of a series of papers on Azadkia and Chatterjee's brilliant idea. Its real meat is a new CLT that solves their 2nd conjecture. A complete storyline can be found in this slide deck:
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@mathSTb
arXiv math.ST Statistics Theory
3 years
Hongjian Shi, Mathias Drton, Fang Han: On Azadkia-Chatterjee's conditional dependence coefficient
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@johnleibniz
Fang Han
1 year
Ok, the literature review is done: Beran (1997) showed that in LAN models, bootstrap consistency is equivalent to that the estimator is regular; should be a textbook result IMHO.
@johnleibniz
Fang Han
1 year
Peter Bickel just pointed out to me that Hodges's estimator is another example; bootstrap fails then at mu=0 (Beran 1982). It then occurred to me that Andrea Rotnitzky also mentioned that bootstrap consistency is sth about *regular* estimators. Would be nice to see a theory!
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@johnleibniz
Fang Han
3 years
@bbstats @adad8m @octonion @_bakshay distance correlation is more efficient in testing independence, but is not distribution-free, is sensitive to outliers, and cannot capture perfect dependence (i.e., it is not 1 iff Y is a measurable function of X). Check my Bernoulli news article for more:
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@johnleibniz
Fang Han
15 days
We now improve the rate to n^{-1/2}, the obviously optimal one.
@johnleibniz
Fang Han
1 year
To appear in 𝗜𝗘𝗘𝗘 𝗧𝗿𝗮𝗻𝘀𝗮𝗰𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗜𝗻𝗳𝗼𝗿𝗺𝗮𝘁𝗶𝗼𝗻 𝗧𝗵𝗲𝗼𝗿𝘆. Do check Teh and Polyanskiy's follow-up work, which improved the rate of ours from n^{-1/10} to n^{-1/4} via a smart use of Hadamard’s three-circle theorem.
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@johnleibniz
Fang Han
6 months
I should have added a reference to this tweet: the super impressive Artstein-Ball-Barthe-Naor 2004 JAMS paper. Simply elegant and powerful.
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@johnleibniz
Fang Han
6 months
If you keep convoluting the same density function but deliberately keep the mean and variance stable, then it will eventually converge to a distribution with the maximum entropy under that mean/variance constraint. CLT is confirming the second law of thermodynamics.
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@johnleibniz
Fang Han
4 months
The real challenge in VC type theorems, which is usually hidden in learning theory, is the measurability requirement on the studied objects. This is a long-forsaken bug that one you noticed, is hard to get away from.
@mraginsky
Maxim Raginsky
4 months
@vpatryshev Some probabilists recognized the importance of that work early on, for example Richard Dudley played a big role in spreading awareness of the VC work in the West.
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@johnleibniz
Fang Han
3 years
guess who is a big fan of Leibniz🤪
@UWStat
UW Statistics
3 years
We are proud to announce that two of our core faculty members recently got promoted to new appointments in UW Statistics. Congratulations to Fang Han and Alex Luedtke for their accomplishments! Read about them at: @johnleibniz @aluedtke
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@johnleibniz
Fang Han
3 years
New paper in Biometrika. Nothing particularly technically challenging but, hey, only 16-page long yet with Sourav Chatterjee, Holger Dette, Jaroslav Hájek, Wassily Hoeffding, Jack Kiefer, Lucien Le Cam, Murray Rosenblatt, and many other great statisticians in😍
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@johnleibniz
Fang Han
2 years
Probably worth mentioning: Chatterjee's correlation coefficient is both asymptotically normal and bootstrap INCONSISTENT. I do not recall seeing a second such example except for some artifacts (Bickel&Freedman, 1981?).
@johnleibniz
Fang Han
2 years
Sourav's comment on Lin and Han (2022, ):
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@johnleibniz
Fang Han
1 year
Here is the proof, executed by the magnificent @zzzxlin : , where discussion with @hagmnn and @molivarego on Twitter was acknowledged (and much appreciated!). Still seeking more examples that are root-n consistent, ASN, but bootstrap inconsistent🤔
@johnleibniz
Fang Han
2 years
Probably worth mentioning: Chatterjee's correlation coefficient is both asymptotically normal and bootstrap INCONSISTENT. I do not recall seeing a second such example except for some artifacts (Bickel&Freedman, 1981?).
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@johnleibniz
Fang Han
7 months
For people that like matching, rank-based statistics, and nonparametric regression with generated covariates🤓 A collaborative work with the awesome Matias and the amazing Zhexiao @zzzxlin 😍
@mathSTb
arXiv math.ST Statistics Theory
7 months
Matias D. Cattaneo, Fang Han, Zhexiao Lin: On Rosenbaum's Rank-based Matching Estimator
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@johnleibniz
Fang Han
2 years
Here comes the great master: 𝘔𝘦𝘢𝘴𝘶𝘳𝘦𝘴 𝘰𝘧 𝘪𝘯𝘥𝘦𝘱𝘦𝘯𝘥𝘦𝘯𝘤𝘦 𝘢𝘯𝘥 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯𝘢𝘭 𝘥𝘦𝘱𝘦𝘯𝘥𝘦𝘯𝘤𝘦 by Peter Bickel.
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@johnleibniz
Fang Han
28 days
A simpler example is Kendall's tau, for which the U-statistic version is more efficient than the sample-mean version (centralize using the pop mean). However, the same observation does not apply to Pearson's correlation, for which if you know the pop mean, you should use it.
@pengding00
Peng Ding
30 days
IPW with the estimated propensity score is another example. The first-stage estimation reduces the asymptotic variance, which surprises many people. A recent paper is Also, Newey&McFadden chapter 6 is about "two-step estimation"
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@johnleibniz
Fang Han
2 years
Handled by the fabulous AE @mraginsky and fresh new in the 𝗜𝗘𝗘𝗘 𝗧𝗿𝗮𝗻𝘀𝗮𝗰𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗜𝗻𝗳𝗼𝗿𝗺𝗮𝘁𝗶𝗼𝗻 𝗧𝗵𝗲𝗼𝗿𝘆, this paper gives the information limit of general order spline regressions. Very likely the most technical paper I will ever be able to write.
@mathSTb
arXiv math.ST Statistics Theory
4 years
Yandi Shen, Qiyang Han, Fang Han : On a phase transition in general order spline regression
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@johnleibniz
Fang Han
2 years
My take on statistical reasoning (now often rebranded as “causal XXX”): NO magic, just assumptions. Statistical reasoning is, extremely unsatisfactorily to a perfectionist, entirely a play of assumptions.
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@johnleibniz
Fang Han
1 year
To appear in 𝗜𝗘𝗘𝗘 𝗧𝗿𝗮𝗻𝘀𝗮𝗰𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗜𝗻𝗳𝗼𝗿𝗺𝗮𝘁𝗶𝗼𝗻 𝗧𝗵𝗲𝗼𝗿𝘆. Do check Teh and Polyanskiy's follow-up work, which improved the rate of ours from n^{-1/10} to n^{-1/4} via a smart use of Hadamard’s three-circle theorem.
@johnleibniz
Fang Han
3 years
This is a fun project: we found that under the Gaussian-smoothed optimal transport distance, the estimation accuracy of the NPMLEs can be accelerated to a polynomial rate and is in sharp contrast to the \log n-type rates based on the unsmoothed Wasserstein one.
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@johnleibniz
Fang Han
2 years
@daniela_witten @Lizstuartdc @raziehnabi @nataliexdean @BetsyOgburn @analisereal @yayyyates I am still digesting two facts that (a) I am on the same flight with a COPSS winner and (b) she is sitting in the economic but not business class🧐
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@johnleibniz
Fang Han
3 years
In case you have not known yet, in this issue there is one short article written by me (!), covering some of our recent efforts to extend rank correlations to higher dimensions. Please enjoy it ☺️
@BernoulliSoc
Bernoulli Society
3 years
Forthcoming issue of Bernoulli News is now available!
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@johnleibniz
Fang Han
7 months
Just out!: An interview with Marc Hallin, accurately described in the abstract as "One of the most brilliant mathematical statisticians of our time". He is a role model admired by many of us.
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@johnleibniz
Fang Han
1 year
Peter Bickel just pointed out to me that Hodges's estimator is another example; bootstrap fails then at mu=0 (Beran 1982). It then occurred to me that Andrea Rotnitzky also mentioned that bootstrap consistency is sth about *regular* estimators. Would be nice to see a theory!
@johnleibniz
Fang Han
1 year
Here is the proof, executed by the magnificent @zzzxlin : , where discussion with @hagmnn and @molivarego on Twitter was acknowledged (and much appreciated!). Still seeking more examples that are root-n consistent, ASN, but bootstrap inconsistent🤔
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@johnleibniz
Fang Han
2 years
Here comes another great master: 𝗦𝗼𝘂𝗿𝗮𝘃 𝗖𝗵𝗮𝘁𝘁𝗲𝗿𝗷𝗲𝗲 surveys recent developments in measures of association, including his own rank correlation coefficient!
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@johnleibniz
Fang Han
11 months
Although bootstrap could fail, m out of n bootstrap will never. Check Dette and @k2daroll 's recent work on the validity of m out of n bootstrap for inferring Chatterjee's rank correlation. It is an elegant work.
@johnleibniz
Fang Han
1 year
Ok, the literature review is done: Beran (1997) showed that in LAN models, bootstrap consistency is equivalent to that the estimator is regular; should be a textbook result IMHO.
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@johnleibniz
Fang Han
1 year
Both "On the power of Chatterjee’s rank correlation" and "On boosting the power of Chatterjee’s rank correlation" are now among 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗿𝗲𝗮𝗱 𝗮𝗿𝘁𝗶𝗰𝗹𝗲𝘀 𝗶𝗻 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮. Take a look!
@johnleibniz
Fang Han
2 years
"On the power of Chatterjee's rank correlation" is currently among 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗿𝗲𝗮𝗱 𝗮𝗿𝘁𝗶𝗰𝗹𝗲𝘀 𝗶𝗻 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮; please take a look if interested in measuring functional dependence, Le Cam's method, or rank/permutation statistics.
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@johnleibniz
Fang Han
2 years
Its sister paper, "On boosting the power of Chatterjee's rank correlation", was also just 𝗮𝗰𝗰𝗲𝗽𝘁𝗲𝗱 𝘁𝗼 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗸𝗮. Key message: scaling up the # of nearest neighbors can boost Chatterjee's power to near parametric.
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@johnleibniz
Fang Han
4 years
Yup, that is true; we are hiring
@daniela_witten
Daniela Witten
4 years
The rumors are true.... UW Statistics is really hiring 2 tenure-track assistant professors!! 👩‍🎓👨‍🎓📚 Apply before 10/20 for full consideration! 📅✍️💻 PLEASE RETWEET🔊🔊🔊
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@johnleibniz
Fang Han
2 years
Now published in 𝗕𝗶𝗼𝗺𝗲𝘁𝗿𝗶𝗰𝘀, . Short message: 𝐭𝐚𝐤𝐢𝐧𝐠 𝐩𝐚𝐢𝐫𝐰𝐢𝐬𝐞 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐜𝐞𝐬 creates symmetry (regardless of how peculiar X is, X-X' is always symmetric around, right?) and helps make statistical methods more robust.
@arxiv_org
arxiv
3 years
Robust Functional Principal Component Analysis via Functional Pairwise Spatial Signs.
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@johnleibniz
Fang Han
3 years
For the record, ML does not replace nonparametric regression either; it needs tons of misinformation to say so.
@lewbel
Arthur Lewbel
3 years
This is a commonly held belief - that ML replaces econometrics. It’s wrong. ML only replaces nonparametric regression (including its use for forecasting). ML alone doesn’t handle most econometric issues, including identification, causality, endogeneity, selection, and attrition.
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@johnleibniz
Fang Han
1 month
One thing to note is that this bound no longer holds if we replace the population mean by the sample mean in centralization: the latter yields a t-statistic which is of course heavy-tailed.
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@johnleibniz
Fang Han
3 years
Magnificent 🤩
@adad8m
adad8m🦞
3 years
Graphical comparison between the standard (linear) #correlation and the Chatterjee's "rank correlation" recently introduced in #statistics #probability @johnleibniz @_bakshay
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@johnleibniz
Fang Han
3 years
so proud of Chao, best collaborator ever 😊
@InstMathStat
IMS
3 years
Dr. Chao Gao, University of Chicago, receives the 2021 IMS Tweedie Award “for groundbreaking contributions to robust statistics, including establishing connections with generative adversarial networks, network analysis, and high-dimensional statistical inference.”
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@johnleibniz
Fang Han
3 years
@daniela_witten Compared to this: presenting in a median-sized workshop when the 3-year old walked in, dancing around, and insisting on your help to pee. True story 🤦‍♂️
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@johnleibniz
Fang Han
4 years
New in the 𝗔𝗻𝗻𝗮𝗹𝘀 𝗼𝗳 𝗦𝘁𝗮𝘁𝗶𝘀𝘁𝗶𝗰𝘀: shape constraint helps to estimate a piecewise constant (PC) signal. By-product: the first linear-time algorithm to compute ALL isotonic PC fits.
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@johnleibniz
Fang Han
3 years
This is a fun project: we found that under the Gaussian-smoothed optimal transport distance, the estimation accuracy of the NPMLEs can be accelerated to a polynomial rate and is in sharp contrast to the \log n-type rates based on the unsmoothed Wasserstein one.
@mathSTb
arXiv math.ST Statistics Theory
3 years
Fang Han, Zhen Miao, Yandi Shen: Nonparametric mixture MLEs under Gaussian-smoothed optimal transport distance
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@johnleibniz
Fang Han
3 years
I am 100% endorsing this tweet... looking at the weather forecast for the next 10 days, I think I am depressed. (kidding. Seattle is super awesome. Please apply; @UWStat has a teaching prof position!)
@daniela_witten
Daniela Witten
3 years
Conversation with my husband…. #Seattle 😆 😢 😭
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@johnleibniz
Fang Han
2 years
@sp_monte_carlo Ask the right question, which is usually just about some small-dim functional but absolutely not the whole distribution.
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@johnleibniz
Fang Han
2 years
Sourav's comment on Lin and Han (2022, ):
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@johnleibniz
Fang Han
2 years
Here comes another great master: 𝗦𝗼𝘂𝗿𝗮𝘃 𝗖𝗵𝗮𝘁𝘁𝗲𝗿𝗷𝗲𝗲 surveys recent developments in measures of association, including his own rank correlation coefficient!
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@johnleibniz
Fang Han
1 year
@kareem_carr Sample variance is a U-statistic of the kernel K(x,y)=(x-y)^2/2.
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@johnleibniz
Fang Han
2 years
@maxhfarrell @paulgp @jt_kerwin @causalinf @marcfbellemare @instrumenthull @pedrohcgs You are exactly right, Max! However, there is no rigorous proof about this claim until this recent paper (?). Any comment would be greatly appreciated!
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@johnleibniz
Fang Han
1 year
What a list!!! @zzzxlin first meta and now Jane street, wow🤩
@yminsky
Yaron (Ron) Minsky
1 year
Exciting news! Jane Street has announced the winner's of its first Graduate Research Fellowship: It was a great process, and we were all deeply impressed with the quality of the applicants.
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@johnleibniz
Fang Han
3 years
@ProfRachelGaN simple; do them in weekdays😄
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@johnleibniz
Fang Han
7 months
@AngYu_soci perhaps also worth noting: replacing a PS estimate by the *true* ps also leads to an inefficient ATE estimator; IMO this is one of the best results ever obtained in mathematical statistics.
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@johnleibniz
Fang Han
2 years
@ben_golub Conditional probability (and conditional expectation) is a monster and better left to the second half (when students are expecting materials to be challenging).
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@johnleibniz
Fang Han
4 years
Fresh in 𝐉𝐀𝐒𝐀, with Mathias Drton @TUM_Mathematics and my student Hongjian Shi @UW . Statistical inference built on optimal-transport-induced multivariate ranks. Distribution-freeness and test consistency are simultaneously achieved.
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@johnleibniz
Fang Han
3 years
@justapc @adad8m @_bakshay It is a consistent measure of dependence, namely, it is 0 iff X is independent of Y. However, Chatterjee’s correlation is not uniformly consistent, namely, problems may occur along a special curve.
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@johnleibniz
Fang Han
4 years
@daniela_witten I thought it is model-based inference under the umbrella of (categorical) time series prediction, i.e., we observe X_t (t<=T) and accordingly build a CI for X_{T+1}. For a simple Markov chain model with three states (sun, rain, cloudy), 30% is the transition prob.
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@johnleibniz
Fang Han
3 years
@PreetumNakkiran @avshrikumar Check also this paper (of mine) for some most recent progress on Chatterjee’s rank correlation: . A literature has been quickly built up in the past two years.
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@johnleibniz
Fang Han
2 years
@wu_biostat (1) Permutation uses the structure of the null hypothesis and is thus more "efficient" (Le Cam, Hajak, Bickel, Hallin). (2) Permutation usually can give "uniformly valid" inference bounds (easy?). (3) Permutation is more robust (Romano).
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@johnleibniz
Fang Han
3 years
If you enjoyed reading our previous Biometrika paper (), you may also like to read , where we overcome the power loss of Chattejee's original proposal by scaling up # of nearest neighbours! Technically quite challenging this time.
@johnleibniz
Fang Han
3 years
New paper in Biometrika. Nothing particularly technically challenging but, hey, only 16-page long yet with Sourav Chatterjee, Holger Dette, Jaroslav Hájek, Wassily Hoeffding, Jack Kiefer, Lucien Le Cam, Murray Rosenblatt, and many other great statisticians in😍
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@johnleibniz
Fang Han
4 years
@daniela_witten Hmm... so can we interpret “percent chance of rain” as the conditional probability of “tomorrow is rainy” given everything obtainable until now?
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@johnleibniz
Fang Han
2 years
@ben_golub In the beginning there were Pascal and Fermat, and de Moivre. They debated and debated. Then came Kolmogorov, who taught measure theory to all. Alas, we now know the conditional probability is just a Markov kernel definable over a Polish space, but does anyone still care?
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@johnleibniz
Fang Han
1 year
@itsbradross @jiafengkevinc @jt_kerwin The exact argument was made in Abadie and Imbens' (2016, ECMA) paper, where they showed that the Donsker-type condition in the original matching outcome model can be substantially weakened by using the propensity score; at the cost of efficiency, though.
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@johnleibniz
Fang Han
7 months
@AngYu_soci The high-level reason is simple: simple parametric model eliminates too much information, while a nonparametric reg with a *right* order keeps a good balance between estimation accuracy and info reservation.
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@johnleibniz
Fang Han
9 months
It is rare to encounter such a degree of candor on the internet.
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@johnleibniz
Fang Han
2 years
@paulgp @maxhfarrell @jt_kerwin @causalinf @marcfbellemare @instrumenthull @pedrohcgs Check the thread here: In short, biased-corrected matching is doing double machine learning.
@johnleibniz
Fang Han
3 years
: Our holiday gift to all fans of matching methods: in strong contrast to the common belief, Abadie and Imbens's bias-corrected nearest neighbor (NN) matching actually already gives a doubly robust and semiparametrically efficient estimator of the ATE.
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@johnleibniz
Fang Han
2 years
@hagmnn My conjecture is that any statistic that is not asymptotically linear (=\sum g(X_i)+small order terms) will have trouble. And it just occurs to me that Abadie&Imbens 2008 is another example (ASN but bootstrap inconsistent).
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@johnleibniz
Fang Han
3 years
@PreetumNakkiran @avshrikumar It does not matter; as long as the model is “regular”, Chatterjee’s correlation is inefficient. Chatterjee’s heuristic does not work mathematically; cf. the Biometrika paper (of mine) mentioned above.
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@johnleibniz
Fang Han
2 years
@jiafengkevinc OMG, are we going to teach measure theory on Twitter now???😍😍😍
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@johnleibniz
Fang Han
3 years
@ThosVarley @adad8m @_bakshay Chatterjee correlation comes from the law of total variance; a Chatterjee correlation of value 0.5 means that averagely half of Var(I(Y>.)) can be explained by that conditional on X.
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@johnleibniz
Fang Han
3 years
@vadimZip @jhubiostat Too shy to reply anything meaningful🤣
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@johnleibniz
Fang Han
1 year
@LarsvanderLaan3 Yup, I was just talking about this with Jon Wellner several days ago and was set to prove it myself. But if course, Beran got it 25 years ahead me : )
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@johnleibniz
Fang Han
2 years
@UnibusPluram @kareem_carr (1) Yes, working models are useful, and some (e.g., normal regression that leads to OLS) are super robust; (2) Parametric models can make sen from time to time; (3) nonparametric methods have their own problems, e.g., tuning parameters is a rabbit hole.
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@johnleibniz
Fang Han
2 years
In this department, we use it for everything that involves a faculty vote; it works like a charm.
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@johnleibniz
Fang Han
2 years
@pedrohcgs @maxhfarrell Check the thread I made here: In short, biased-corrected matching is doing double machine learning.
@johnleibniz
Fang Han
3 years
: Our holiday gift to all fans of matching methods: in strong contrast to the common belief, Abadie and Imbens's bias-corrected nearest neighbor (NN) matching actually already gives a doubly robust and semiparametrically efficient estimator of the ATE.
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@johnleibniz
Fang Han
4 months
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@johnleibniz
Fang Han
6 months
@_bakshay Can be traced back to Shannon and Lieb; check the 2nd paragraph of .
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@johnleibniz
Fang Han
4 years
@analisereal @daniela_witten @tdietterich @lucylgao Define a_{k,1}, .., a_{k,k} to be the k "optimal centre points" such that M_k:=E{\min_j \| X - a_{k,j} \|^2} is minimized. My interpretation of the null hypothesis is H_0: M_k=M_{k-1}.
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@johnleibniz
Fang Han
1 year
@zzzxlin , still a first-year PhD student, but already a finalist for Meta PhD fellowship🤩
@neksec
Nektarios Leontiadis
1 year
Meta Research PhD Fellowship award winners for 2023 have been announced! Congratulations to all these bright minds!
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@johnleibniz
Fang Han
4 years
@daniela_witten Oh yes, there is actually a widespread campus legend saying that Padelford was designed to be riot-proof; check here
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@johnleibniz
Fang Han
2 years
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@johnleibniz
Fang Han
7 months
@Apoorva__Lal @pengding00 @zzzxlin The paper suggests a constant/rate choice for M based on the minimax theory and simulations. No idea about how to relate it to OT, though😃
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@johnleibniz
Fang Han
2 years
@daniela_witten a landmark paper
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@johnleibniz
Fang Han
8 months
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@johnleibniz
Fang Han
2 years
This is the tweet of the month.
@NikhilBasavappa
Nikhil Basavappa
2 years
i don’t know how to explain this but this is IV regression
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@johnleibniz
Fang Han
2 months
@ben_golub He is still an undergraduate, Ben!
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@johnleibniz
Fang Han
3 years
(b) The term K_M(i)/M above, introduced in Abadie and Imbens (2006), constitutes a consistent and efficient density ratio estimator. Even better, it is one-step, of near-linear computation complexity, and is statistically optimal, the first one to gain all three simultaneously.
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@johnleibniz
Fang Han
1 year
It is an amazing gathering! Thanks for putting out such a great program, Fabrizio 🤩
@fbdurante
Fabrizio Durante
1 year
The 40th Linz Seminar on " #Copulas - Theory and Applications" ended today. Thanks to all participants and to invited speakers for brilliant talks and discussions. Many problems have been solved. Many others are still open!
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@johnleibniz
Fang Han
2 years
@Apoorva__Lal check Section 3 in
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@johnleibniz
Fang Han
1 month
@ChengGao12 I hope to post the first 8 chapters online in a month🤪
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