K-Means Clustering DATA-SCIENCE-FOUNDATIONS Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   Which condition indicates that K-means has converged?

   • AThe centroids no longer change between iterations.
   • BThe within-cluster sum of squares reaches zero.
   • CThe number of iterations reaches the maximum allowed.
   • DThe data points are sorted in ascending order.
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2. 22foundation · easy

   Which of the following is an assumption of K-means clustering?

   • AClusters are roughly spherical and of similar size.
   • BAll features are categorical.
   • CThe data contains no outliers.
   • DClusters can be arbitrarily shaped and overlapping.
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4. 23foundation · easy

   In K-means, what does a cluster centroid represent?

   • AThe median of all data points assigned to that cluster.
   • BThe mean of all data points assigned to that cluster.
   • CThe point that is closest to all other points in the cluster.
   • DThe most frequent value among the points in the cluster.
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5. 24foundation · easy

   How should categorical variables be handled before applying K-means?

   • AThey should be encoded into numeric values, such as one-hot encoding.
   • BThey can be used directly as strings.
   • CThey should be removed from the dataset.
   • DThey should be replaced with their alphabetical order.
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6. 25foundation · easy

   What is the primary purpose of the K-means++ initialization strategy?

   • ATo ensure all clusters have the same number of points.
   • BTo spread out initial centroids to reduce the chance of poor local optima.
   • CTo speed up the assignment step by using a faster distance calculation.
   • DTo automatically determine the optimal number of clusters k.
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