Week 1 of 12 · Foundations

Data-Centric Thinking, On the Job

Turn your next real shift into a field study — and start seeing quality problems the way a lead does

Day 4 ~60 minutes + your shift Field Day

Day 4 of 66

Model-centric vs data-centric — the mindset shift

When a model underperforms, there are two instincts. The model-centric instinct says "change the model — more parameters, new architecture, more training." The data-centric instinct says "the model is fine; the data is noisy, inconsistent, or missing cases — fix that." Andrew Ng's central argument is that for most mature systems, the data-centric path is faster, cheaper, and the one most teams neglect.

Core Theory

Why consistent labels beat more labels

Imagine two tutors scoring the same images. If they systematically disagree about what "good prompt adherence" means, the model receives contradictory signal — for the same image it's told both "good" and "bad." The model can't learn a clean boundary from noisy labels; it averages the confusion. Ng's research showed that tightening label consistency often beats both adding data and changing the model. This is why your Week 2 (rubrics) and Week 3 (agreement) exist: consistency is a lever you control.

A lead's reflex

When someone says "the model is bad at X," a data lead doesn't reach for the model. They ask: What data taught it X? Was that data consistent? Did the rubric cover the cases it's failing on? Is our eval even measuring X honestly? Those four questions are your job in a sentence.

Today is a field study

This is a "Field Day" — the work happens during your actual xAI shift. You're going to do your normal tutoring, but with a second layer of attention running. You're observing the system, not just doing the task.

Field Observation

Watch your own work like a lead would

  1. Catch one ambiguous task. During your shift, find a single item where you weren't sure how to label it. Write down: what made it ambiguous? Was it a gap in the guideline, or genuinely a hard case?
  2. Spot one consistency risk. Identify a place where you suspect another tutor would label differently than you. That gap is a future inter-annotator-agreement problem (Week 3) and usually a guideline problem (Week 2).
  3. Name the data product. For your shift's main task, state which of the four products it produces and what the model learns. Then ask the lead's reflex questions about it.
  4. One improvement. Write a single concrete change to the guideline or process that would make the data more consistent. This is your first act of data leadership — proposing an improvement, not just following the rule.
Keep it private and policy-safe

Record your observations in general terms in your own notebook — the mechanics and your reasoning, not confidential prompts, customer data, or anything under NDA. The transferable skill is the habit of systems observation, and that's fully yours to keep.

Read alongside

article
Data-Centric AI
Andrew Ng / DeepLearning.AI
The competition that flipped the field's attention from models to data. Read the motivation; absorb the mindset.
15 min
The lead move

A tutor proposes one guideline fix. A lead turns "the model is bad at X" into a data investigation: quantify the inconsistency, trace it to the rubric clause that allows it, ship the fix, and report the lift as a number. The reflex becomes a repeatable diagnostic the team runs — not a one-off observation.

Say this in an interview: "When someone says 'the model is bad at X,' I don't reach for the model. I ask what data taught X, whether it was consistent, whether the rubric covered the failing cases, and whether the eval even measures X honestly — and then I fix the data and show the lift."

Today's Takeaways