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Computer science · University

Data quality and cleaning

An observation where a required measurement is absent.

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Prerequisites

Algebra and basic statistics.

Study notes

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

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

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

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

    1. Outlier
    2. Data type
    3. Validation rule
    4. Missing value

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

  3. Which statement about Missing value is most accurate?

    1. An observation unusually far from the main pattern and requiring contextual review.
    2. A stated condition used to check whether data are plausible or acceptable.
    3. The representation and allowed operations for a variable.
    4. An observation where a required measurement is absent.

  4. Explain one important difference between Missing value and Outlier.

Answers and marking guidance

Answers and marking notes
  1. Data type

    The scenario directly calls for Data type.

  2. Validation rule

    The intended concept is Validation rule.

  3. An observation where a required measurement is absent.

    The definition in the lesson notes gives the required condition.

  4. 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.

Further reading and review references

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