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Computer science · lesson 1 of 4

Data quality and cleaning

An observation where a required measurement is absent.

University8 practice questionsNotes + worked examples
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Learn the ideas

Prerequisites: Algebra and basic statistics.

Missing value

An observation where a required measurement is absent.

Outlier

An observation unusually far from the main pattern and requiring contextual review.

Data type

The representation and allowed operations for a variable.

Validation rule

A stated condition used to check whether data are plausible or acceptable.

Worked examples

Example 1

Which term best matches this description: An observation where a required measurement is absent.

Missing value is the matching concept in this lesson.

Missing value

Example 2

Which term best matches this description: An observation unusually far from the main pattern and requiring contextual review.

Outlier is the matching concept in this lesson.

Outlier

Check your understanding

8 questions

Decimals or fractions are accepted for numeric answers. Proofs and written responses use sample answers and require human marking. This is practice, not a protected examination.

1 Which term best matches this description: An observation where a required measurement is absent.

Show answer and explanation

Missing value

Missing value is the matching concept in this lesson.

2 Which term best matches this description: An observation unusually far from the main pattern and requiring contextual review.

Show answer and explanation

Outlier

Outlier is the matching concept in this lesson.

3 Which concept would you apply first in a situation where the representation and allowed operations for a variable.

Show answer and explanation

Data type

The scenario directly calls for Data type.

4 Name the concept described as: A stated condition used to check whether data are plausible or acceptable.

Show answer and explanation

Validation rule

The intended concept is Validation rule.

5 Which statement about Missing value is most accurate?

Show answer and explanation

An observation where a required measurement is absent.

The definition in the lesson notes gives the required condition.

6 Explain one important difference between Missing value and Outlier.

Sample answer and marking guidance

Missing value: An observation where a required measurement is absent. Outlier: An observation unusually far from the main pattern and requiring contextual review.

Credit a clear distinction using both definitions and an appropriate example if supplied.

7 Give a short example showing how Data type would be used in practice.

Sample answer and marking guidance

A valid example should demonstrate this idea: The representation and allowed operations for a variable.

Credit a relevant scenario that applies the concept rather than merely naming it.

8 Summarize why Validation rule matters in the lesson “Data quality and cleaning”.

Sample answer and marking guidance

Validation rule matters because A stated condition used to check whether data are plausible or acceptable.

Credit the core purpose, scope and any important limitation from the notes.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.