How would you develop a model to identify plagiarism?

Data Science, AI and ML
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#1

How will you define the number of clusters in a clustering algorithm?

#2

Though the Clustering Algorithm is not specified, this question is mostly in reference to K-Means clustering where “K” defines the number of clusters. The objective of clustering is to group similar entities in a way that the entities within a group are similar to each other but the groups are different from each other.

For example, the following image shows three different groups.

Clustering - Data Science Interview Questions - Edureka
Clustering - Data Science Interview Questions - Edureka2048×537 98.4 KB
Within Sum of squares is generally used to explain the homogeneity within a cluster. If you plot WSS for a range of number of clusters, you will get the plot shown below.

Clustering Plots - Data Science Interview Questions - Edureka

  • The Graph is generally known as Elbow Curve.
  • Red circled point in above graph i.e. Number of Cluster =6 is the point after which you don’t see any decrement in WSS.
  • This point is known as bending point and taken as K in K – Means.

This is the widely used approach but few data scientists also use Hierarchical clustering first to create dendograms and identify the distinct groups from there.

#3

It depends on the clustering algorithm. To give a few examples:

K-means uses the bend in an elbow plot based on the within-cluster sum of squares metric.

Hierarchical Clustering uses dendrograms to determine its clusters.

You can also use a silhouette plot to help to determine if your clusters are sufficient.