The worst taught skill in machine learning is model validation.

If you can’t validate your models well, you have no idea if they will actually work.

Here are 3 steps I’d take if I was relearning model validation from scratch 🧵

1. Learn the essential evaluation metrics

Think accuracy should be your primary metric? You’re sorely mistaken.

Most of the best metrics instead focus on how far your were from the correct answer. Think RMSE and MAE.

Others point to how well calibrated your model is, like F1.
2. Learn the common forms of cross validation

Before diving in too deep, make sure you understand the basics.

You can’t become an expert in validation in the classroom, but knowing what is out there (simple k-fold, stratified, grouped, roll forward, etc.) is crucial.
3. Read old Kaggle competition solutions

Every day, or multiple times a week, pick an old Kaggle competition.

Read every solution that is posted and skip to their validation schemes.

There are nuances to every dataset, and this is the best way to see how pros navigate them.
4. Build simple models and try different CV schemes

Get a dataset and create a random test set.

Then, build some simple models and switch validation strategies in and out and see how well your models generalize for each scheme.

This will cement the importance of validation.
5. Go and do it. A lot.

You will only improve at validation if you apply it to a ton of datasets.

If you stop after step 2, your skills will not be good enough. Full stop.

Never rest on your laurels. There is always something new to learn, and some new trick you can use.
This is a pretty general outline, but I plan on diving into the specifics on evaluation metrics and CV schemes in the future.

I also discussed them on a podcast with @bhutanisanyam1 here: https://t.co/AiGAe1zBH3

Follow me @marktenenholtz so that you don’t miss it!

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How can we use language supervision to learn better visual representations for robotics?

Introducing Voltron: Language-Driven Representation Learning for Robotics!

Paper: https://t.co/gIsRPtSjKz
Models: https://t.co/NOB3cpATYG
Evaluation: https://t.co/aOzQu95J8z

🧵👇(1 / 12)


Videos of humans performing everyday tasks (Something-Something-v2, Ego4D) offer a rich and diverse resource for learning representations for robotic manipulation.

Yet, an underused part of these datasets are the rich, natural language annotations accompanying each video. (2/12)

The Voltron framework offers a simple way to use language supervision to shape representation learning, building off of prior work in representations for robotics like MVP (
https://t.co/Pb0mk9hb4i) and R3M (https://t.co/o2Fkc3fP0e).

The secret is *balance* (3/12)

Starting with a masked autoencoder over frames from these video clips, make a choice:

1) Condition on language and improve our ability to reconstruct the scene.

2) Generate language given the visual representation and improve our ability to describe what's happening. (4/12)

By trading off *conditioning* and *generation* we show that we can learn 1) better representations than prior methods, and 2) explicitly shape the balance of low and high-level features captured.

Why is the ability to shape this balance important? (5/12)

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The first ever world map was sketched thousands of years ago by Indian saint
“Ramanujacharya” who simply translated the following verse from Mahabharat and gave the world its real face

In Mahabharat,it is described how 'Maharishi Ved Vyasa' gave away his divine vision to Sanjay


Dhritarashtra's charioteer so that he could describe him the events of the upcoming war.

But, even before questions of war could begin, Dhritarashtra asked him to describe how the world looks like from space.

This is how he described the face of the world:

सुदर्शनं प्रवक्ष्यामि द्वीपं तु कुरुनन्दन। परिमण्डलो महाराज द्वीपोऽसौ चक्रसंस्थितः॥
यथा हि पुरुषः पश्येदादर्शे मुखमात्मनः। एवं सुदर्शनद्वीपो दृश्यते चन्द्रमण्डले॥ द्विरंशे पिप्पलस्तत्र द्विरंशे च शशो महान्।

—वेद व्यास, भीष्म पर्व, महाभारत


Meaning:-

हे कुरुनन्दन ! सुदर्शन नामक यह द्वीप चक्र की भाँति गोलाकार स्थित है, जैसे पुरुष दर्पण में अपना मुख देखता है, उसी प्रकार यह द्वीप चन्द्रमण्डल में दिखायी देता है। इसके दो अंशो मे पीपल और दो अंशो मे विशाल शश (खरगोश) दिखायी देता है।


Meaning: "Just like a man sees his face in the mirror, so does the Earth appears in the Universe. In the first part you see leaves of the Peepal Tree, and in the next part you see a Rabbit."

Based on this shloka, Saint Ramanujacharya sketched out the map, but the world laughed