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Daniela Witten Profile picture
Daniela Witten
@daniela_witten
dorothy gilford endowed chair and prof of stat/biostat @uw. all views my own.
Kambiz Profile picture PT Barnum was right Profile picture -No es por la edad- (Karina Rdz Q) Profile picture MLemaire Profile picture Rui Carvalho Profile picture 6 subscribed
Feb 9, 2022 • 4 tweets • 4 min read
****Big news for fans of ISLRv2!!**** #RStats #ISLR #ISL

A TORCH VERSION OF THE DEEP LEARNING LAB (CHAPTER 10) IS NOW AVAILABLE!!! 🎆🤩💯🍾🥳🎉🪅

The original deep learning lab made use of keras, which requires a python installation, and is very finicky.

1/3 Image @dfalbel and @zkajdan translated the Chapter 10 lab into torch, a deep learning library from @rstudio that **doesn't require a python installation**.

It's available here: statlearning.com/resources-seco…

2/3
Dec 26, 2021 • 5 tweets • 2 min read
My daughter and I have been sitting on the tarmac at SeaTac for 6 hours waiting for our flight to take off.

@alaskaair what is going on?! 6 hours is way too long to have a 7yo sitting on a plane, especially without snacks, water, or updates about flight status Also, thankful for our n95s, I can’t see a covered nose anywhere
Oct 2, 2021 • 6 tweets • 2 min read
What I’ve learned during this pandemic… a 🧵

1/ 2/
Aug 5, 2021 • 6 tweets • 3 min read
Finally --- the 2nd edition of ISLR is out!!!!🥳🎉🪅🍾

Well, sort of. 🙄It's "published", but due to shortages in the global paper supply, hard copies won't be available for a bit longer 😢😭🤦‍♀️

You can pre-order a hard copy from Springer/Amazon, & **download the pdf today**! 1/ Image Purchase from Springer: link.springer.com/book/10.1007/9…

Purchase from Amazon: amazon.com/Introduction-S…

Download the pdf today: statlearning.com
2/
Apr 14, 2021 • 7 tweets • 2 min read
A lot of people have reached out to check in on me after this article came out --- in which I use a very colorful analogy to describe the current situation that many mothers in academia face during the pandemic 1/ nytimes.com/2021/04/13/hea… If you reached out, then thank you for the concern. I have been very fortunate: since late Spring 2020, I have had the good fortunate of consistent high-quality childcare for my 3 small children. (Not to mention that I'm senior faculty w/ job security.) 2/
Mar 16, 2021 • 6 tweets • 2 min read
I am loving these recent threads from @j_l_godwin on ADHD + academia. Thank you for sharing your experiences, Jessica --- I have learned a lot, and this new knowledge will help me be a better teacher/mentor for students in the future. Another one:
Jan 17, 2021 • 6 tweets • 3 min read
Since you asked, yes, I will write a thread about the SVD.

The SVD solves the optimization problem in the screenshot (X is nxp).

The k columns of U and V are the 1st k left and right singular vectors of X, and the diagonal elements of D are the 1st k singular values

1/4 Image "Nonnegative matrix factorization" is a bit broad but it is most often used to refer to the optimization problem in this screenshot, which -- as you can see -- is like a distant cousin of the SVD. Sometimes an orthogonality constraint may be placed on the columns of V.

2/4 Image
Oct 29, 2020 • 16 tweets • 5 min read
The new cover article in @NautilusMag is about the sordid history of eugenics in the field of statistics.

I had a conversation with @aubreyclayton a few months ago, when he was beginning his work on this article.

1/🧵 I think this article has a lot of value, as it brings to sharp focus the very racist views of some of the founders of our field: Galton, Pearson, Fisher, in particular. I applaud Aubrey for his very careful research about this topic.

Some screenshots from the article:

2/
Oct 3, 2020 • 5 tweets • 1 min read
WHY DID I SAY A P-VALUE IS A TEST OF SAMPLE SIZE?

THREAD 🧵



Suppose we want to test whether the mean of some random variable X is zero. To keep it simple, X1,...,Xn are i.i.d. N(mu, 1). Testing if mu=0.

1/🧵 Now suppose that IRL mu=0.001 (remember- IRL the null hypothesis never exactly holds!)

The z-test for testing mu=0 involves computing

Z=sqrt(n)*Xbar/sigma

and comparing to a N(0,1) distribution. And sigma=1 by my earlier assumption that X_1,...,X_n are i.i.d. N(mu,1).

2/
Oct 3, 2020 • 13 tweets • 2 min read
FOUR CARDINAL RULES OF STATISTICS 📈📊📉

A thread

1/🧵 ONE: CORRELATION DOES NOT IMPLY CAUSATION.

Yes, I know you know this, but it’s so easy to forget!

Yeah, YOU OVER THERE, you with the p-value of 0.0000001 — yes, YOU!! That’s not causation.

2/
Oct 2, 2020 • 4 tweets • 1 min read
Last week, a paper came out that received a lot of very harsh criticism from the scientific community. First things first: I 100% agree with a lot of that criticism.

Criticizing a paper (or agreeing with others' criticisms of a paper) is okay. That's how science works.

1/ HOWEVER, after seeing the paper, I shot off a careless tweet. It was meant to be lighthearted, but it missed the mark!!!! It came across as a personal attack on the authors.

It was a mistake to have posted it, and I have since deleted it.

2/
Sep 19, 2020 • 4 tweets • 2 min read
Hi scientists, could you please help me understand why this Harvard site says that the FPR of PCR can be as high as 5%?

Is this just due to the risk of sample/lab contamination (hopefully << 5%), or do they consider it a FP if someone who recovered has trace amounts of virus? 1/ Image By contrast this website from MIT is in line with what I thought to be true- virtually no FP from PCR
2/ Image
Sep 11, 2020 • 4 tweets • 2 min read
today my husband said “in a normal year we’d be in air conditioned offices all day and we wouldn’t even notice the horrible air quality”

and that’s the moment I discovered that my husband thinks my office for the past literally 10 years has air conditioning even though it doesn’t have A/C, i do miss it so— for one thing, my office has a door that I can close.

also, who wouldn’t love an office in a building that is ambiguously inspired by either a monastery or a prison? ImageImage
Aug 21, 2020 • 4 tweets • 2 min read
Pre-covid Image And this with @aristeinberg Image
Aug 9, 2020 • 23 tweets • 6 min read
The Bias-Variance Trade-Off & "DOUBLE DESCENT" 🧵

Remember the bias-variance trade-off? It says that models perform well for an "intermediate level of flexibility". You've seen the picture of the U-shape test error curve.

We try to hit the "sweet spot" of flexibility.

1/🧵 This U-shape comes from the fact that

Exp. Pred. Error = Irreducible Error + Bias^2 + Var

As flexibility increases, (squared) bias decreases & variance increases. The "sweet spot" requires trading off bias and variance -- i.e. a model with intermediate level of flexibility.

2/
Aug 7, 2020 • 8 tweets • 2 min read
When I teach cross validation in my Intro to Statistical Learning course, I literally spend a class on “potential pitfalls of CV” and this is the main error I talk about. Happens all the time in published biology literature- not just for methylation data

1/ This error is particularly stressful to me as a statistician, because it means that my data analysis can be totally wrong due to data pre-processing that may have been performed before I ever saw the data and that I don’t know about

2/
Aug 4, 2020 • 4 tweets • 3 min read
It is such an honor to receive the 2021 Breiman Award from @AmstatNews for "outstanding contributions to statistical learning, computational statistics, and their practical applications".

1/4 Image This honor would 100% not have been possible without the mentoring and support that I have received over the years from colleagues @UWBiostat and @UW Stat as well as elsewhere (special shout-out to the one and only @robtibshirani)....

2/4
Jul 24, 2020 • 6 tweets • 1 min read
This is how I feel 99.9% of the time that I watch people cook pasta. Guys this is not that hard.
- Salt the water
- Sauce gets mixed in right away
It isn't rocket science.
Unless you're making soup, do NOT put oil in the water.
I've lost friends over this & I feel OK about that. This tweet proudly brought to you by the daughter of a Neapolitan
Jun 29, 2020 • 5 tweets • 1 min read
I wouldn’t worry - getting COVID under control will be a sinh!!

Or possibly a tanh Actually the issue is asympto(ma)tic
Jun 24, 2020 • 16 tweets • 4 min read
The Fisher Lecture: an epilogue.

I am delighted that COPSS decided to retire the name of the Fisher Award and Lecture, and to create a new COPSS Distinguished Achievement Award and Lecture.

A lot has happened during the past 3 weeks since I posted this original thread.

1/ In the world . . . well, read the news, I can’t give you a recap.

But in case you've been living under a rock . . it’s been a lot.

I’ll focus on just two news items.

2/
Jun 20, 2020 • 4 tweets • 1 min read
When I finished my PhD I told a female statistician (a few years senior to me) that I’d be starting a job @UW.

Her first Q: who will your postdoc advisor be? (A: I was going to be faculty)

Her 2nd Q: what department is your husband’s faculty appointment? (A: 😳 😳 😳) It cuts both ways tho because my husband’s co-workers at the time we’re like “you’re moving all the way to Seattle to go to grad school?!”