Question

• What is Clustering?
• What is the purpose of clustering?
• What assumptions are needed for clustering?
• Why do you need to transform qualitative variables to be presented by numbers in clustering?
• What is the purpose of normalizing quantitative variables?

Answer 1

Solution : i> Clustering : Clustering is a group of data object that belongs to the same class . Clustering helps divide data into a number of subsets. Each of these subsets contain data that is similar to one another.

ii> Purpose of Clustering : The purpose of clustering is to place objects into groups, or clusters, suggested by the data, not defined a priori , such that objects in a given cluster tend to be similar to each other in some sense, and objects in different clusters tend to be dissimilar.

iii> Assumptions in Clustering : The assumptions in clustering are given below :

1. It is always assumed that the sample is representative for the population

2. It is assumed that variables are not correlated; if variables are correlated, remove correlated variables or use distance  measures that compensates for the correlation .