C13 · Topic 2.3 · 40 minutes · DAT-2.A, DAT-2.B, DAT-2.C
Data, metadata and questions
By the end you can:
- Use metadata to interpret a table.
- Form an answerable question.
- Explain how processing can reveal information.
Before this lesson: topics 2.1.
- Metadata
- Data that describes other data, such as units, collection time or meaning of a field.
- Association
- A pattern of related values that does not alone establish causation.
Understand
Data gains meaning through context: a column of 12,18 and 24 could mean ages, minutes or distances. Metadata supplies units, definitions and collection rules. Check what one row represents before counting or combining records; otherwise apparently precise calculations may answer the wrong question.
A programme can filter, combine, summarise or visualise data to reveal patterns that are difficult to see in raw records. Begin with a specific question and identify which fields and population can support it. More data and faster processing do not automatically remove collection bias or missing context.
Worked example
The transport table documents one row per trip, minutes as the time unit and a recorded travel mode.
- The repeated ID C tells us two rows may describe one trip, not two travellers.
- A question about mean time by mode needs valid time and mode values.
- A question about travel speed cannot be answered from time alone because distance was not collected.
Explore each concept
Choose a concept, change its inputs and follow the explanation. Each example models the stated rule or scenario; completing it is practice rather than evidence of mastery.
- Metadata versus primary data
- Descriptive claims versus causes
- Combining records and re-identification
Change it · step through · explain
Change an input, predict what will happen, then advance one step. Read why the state changes, reset and experiment. This fixed teaching model does not save progress or award XP.
Ready · Make a prediction
- QuestionmetadataWaiting
- Time unit metadataminutesWaiting
Ready to explore: Metadata, association and linked data
Why: Change an input, predict the first effect, then advance one step.
Try this: Change one input or choose another listed case. Predict the effect, reset and compare the states and governing rule.
Step through and experiment
Change it · step through · explain
Change an input, predict what will happen, then advance one step. Read why the state changes, reset and experiment. This fixed teaching model does not save progress or award XP.
Ready · Make a prediction
- Input 1deduplicateWaiting
- Input 2excludeWaiting
Ready to experiment
Why: Predict the first change, then advance one step.
Try this: Change only one cleaning policy. Which numerator or denominator changes?
Check a misconception
Claim: Numbers are self-explanatory without units or row definitions.
The same values can represent different quantities; metadata determines an appropriate interpretation.
Guided practice
Identify three metadata details needed for the transport inquiry.
Work with a partner. Make a prediction, compare your reasoning, then identify the rule that supports your answer.
Independent transfer
An analyst asks whether bus travellers are slower per kilometre. What is missing?
Exit check
How does filtering differ from creating a new measured fact?
Write your reasoning before comparing with a classmate. If your teacher assigned this task, submit it through My classes to save your work and receive feedback.
Check yourself
Your practice so far
Check an answer to see its rationale.