skill~300 mindifficulty

Data Quality & Testing

Silent bad data is worse than a failed job; automated quality checks keep downstream analytics trustworthy.

1

Learn it

Treat data quality like unit testing for datasets. Using Great Expectations, declare expectations (not-null, ranges, uniqueness, allowed values), validate batches, and produce data docs. Then wire checks into pipelines so bad data fails fast rather than propagating.

By the end you’ll be able to

  • Define expectations/assertions about a dataset
  • Validate a batch and integrate checks as pipeline gates

Free resources

2

Practice

Set up Great Expectations on a dataset, define 5 expectations, validate a batch, and generate the data docs report.

3

Build it — your output

A validation suite of expectations plus a generated data-quality report on a real dataset.

4

Prove it — check yourself

You’re ready to move on when you can honestly say yes to each:

  • Can you write expectations for null-checks, ranges, and uniqueness?
  • Can you validate a batch and interpret the results?
  • Can you explain where in a pipeline a quality gate belongs?

Do it with AI

Use a free AI tool as your tutor and pair-programmer. Copy a prompt below into Claude, ChatGPT, or Gemini (for building, try Cursor or Copilot).

The habit: Try it yourself first — a little struggle is where the learning actually happens. Then ask for a hint before the answer — never copy blindly.

  • Understand itClaude / ChatGPT / Gemini

    I'm a beginner learning "Data Quality & Testing". Explain it in simple terms with a real-world analogy, then ask me ONE question to check my understanding — don't reveal the answer.

  • PracticeClaude / ChatGPT / Gemini

    Give me 3 short practice problems on "Data Quality & Testing" (my goal: define expectations/assertions about a dataset), from easy to hard. Don't include the solutions yet — I'll try them first, then ask you to check.

  • Get unstuckClaude / ChatGPT / Gemini

    I'm stuck on this exercise about "Data Quality & Testing": [paste your attempt here]. Give me ONE small hint to move forward — do NOT give me the full solution.

  • Build & reviewCursor / Copilot

    Here is my work for a "Data Quality & Testing" task: [paste your code or answer]. Review it: point out what's wrong and WHY, and suggest improvements — but let me make the fixes myself.

  • Prove itClaude / ChatGPT / Gemini

    Quiz me on "Data Quality & Testing". Ask me 5 questions one at a time, wait for my answer each time, then tell me if I'm right and briefly why.

My notes