Visualization of Multivariate Data DATA-SCIENCE-OPTIMIZE Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   In a heatmap of a correlation matrix, what does the color of each cell typically represent?

   • AThe p-value of a statistical test for each pair of variables.
   • BThe standard deviation of each variable.
   • CThe strength and direction of the correlation between two variables.
   • DThe number of missing values in each variable.
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2. 22expert · hard

   A data analyst is using a parallel coordinates plot to explore a dataset with 12 numeric variables. The analyst notices that many lines cross each other, making the plot cluttered and hard to read. Which strategy is most effective for reducing clutter and revealing patterns?

   • AIncrease the line thickness.
   • BReorder the axes to place strongly correlated variables next to each other.
   • CRemove all variables except the first two.
   • DUse a scatterplot matrix instead.
   Reveal Solution Discussion Select an answer first
4. 23application · medium

   A data analyst is working with a dataset of customer transactions with 50 numeric features. The analyst wants to create an interactive 2D scatter plot to explore potential customer segments. The primary goal is to see distinct, well-separated clusters of customers, even if the global distances between clusters are distorted. Which dimensionality reduction technique is most appropriate?

   • At-SNE.
   • BPCA.
   • CA scatterplot matrix of the first 5 features.
   • DA parallel coordinates plot of all 50 features.
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5. 24expert · hard

   A data scientist is exploring a high-dimensional dataset using a t-SNE plot and a scatterplot matrix of the original variables. The scientist brushes a cluster in the t-SNE plot and wants to understand which original variables are most responsible for separating that cluster from the rest. Which approach is most effective?

   • AUse brushing and linking to highlight the cluster in the scatterplot matrix and examine which variable pairs show clear separation.
   • BExamine the t-SNE plot alone to determine variable importance.
   • CCompute the mean of each variable for the entire dataset.
   • DRemove the cluster from the dataset and re-run t-SNE.
   Reveal Solution Discussion Select an answer first
6. 25foundation · easy

   Which statement best describes the purpose of visualizing multivariate data?

   • ATo reduce the number of variables in the dataset to exactly two.
   • BTo reveal patterns, trends, and relationships that are not obvious from summary statistics alone.
   • CTo replace statistical hypothesis testing with visual inspection.
   • DTo make the data easier to store and retrieve from a database.
   Reveal Solution Discussion Select an answer first