← Practice challengesFree companion · 15 minute suggested activity

Produce a complete correction log

Data preparation practice · Use the messy source and independent clean control. Corrections belong in a derived output and a change log.

Learn → Try → ExplainReviewed 2026-10-15

Your task

Describe the three defects and final clean-output checks for retail-orders-messy.csv. Describe the risk of an automatic correction.

Hint

Distinguish formatting fixes from changes in business meaning. Specify what evidence authorizes each correction.

Worked solution

Log duplicate R01, R02 category spelling/spacing and R05 missing status. After evidence-based corrections: 8 unique IDs, known status/channel sets, nonnegative integer cents, completed total 70000. Keep raw file and rejected/duplicate evidence.

What to hand over

Provide raw source fingerprint, old/new values, rule, evidence, affected row IDs and validation totals. A clean-looking table alone is insufficient.

Make the reasoning yours.

Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.

Resume guidance and examples are for learning and preparation only. They do not guarantee interviews, a job offer or employment.

Public registration, payments and new paid enrolment remain disabled. These free resources do not grant access to protected course modules.

Learner dashboard ↗ · Ask a question ↗