NCA-ADS domain - 13% of the exam

Descriptive Analysis and Visualization

Descriptive Analysis and Visualization is 13% of the NVIDIA-Certified Associate: Accelerated Data Science (NCA-ADS) exam. These are the objectives it covers, each with practice questions and worked explanations.

Objectives in this domain

Sample question from this domain

Free sampleDescriptive Analysis and Visualizationeasy

A data scientist is summarising the annual salaries in a dataset that contains a small number of extremely high earner outliers. Which measure of central tendency gives the most representative picture of the typical employee salary?

  • AThe median, because it is resistant to extreme values at the tail of the distribution Correct
  • BThe arithmetic mean, because it incorporates every value in the dataset
  • CThe mode, because the most frequently occurring salary describes what is normal
  • DThe variance, because it quantifies how spread out the salary values are
Explain when the median is preferable to the mean as a measure of central tendency for skewed or outlier-affected data. When a distribution is right-skewed by outliers, the arithmetic mean is dragged toward the tail and overstates where the bulk of observations lie. The median, defined as the middle value of the ordered dataset, is unaffected by the magnitude of extreme values and therefore provides a more representative centre for salary-type data.

Why A is correct: The median splits the ordered distribution at the midpoint and is unaffected by how extreme the highest values are, so it reflects where most salaries actually fall.

Why B is wrong: The mean is tempting because it uses all data points, but outliers pull it far above most employees' salaries, making it unrepresentative of the typical worker.

Why C is wrong: The mode identifies the most common single value, but salary data is often spread across many distinct figures, making the mode a poor summary of the centre.

Why D is wrong: Variance measures dispersion, not central tendency, so it describes spread rather than where a typical salary sits in the distribution.

Other domains in this exam

See also the NCA-ADS cert hub, the study guide, and the cheat sheet.

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