Question 1

A(n)________ or tree graph is a graphical device for displaying clustering results.Vertical lines represent clusters that are joined together.The position of the line on the scale indicates the distances at which clusters were joined.

Accepted Answer

A dendrogram is a graphical device commonly used for displaying clustering results. It has vertical lines that represent clusters and the position of the line on the scale indicates the distances at which clusters were joined. This makes it easy to visually represent the relationships between clusters and how they were merged together.

Question 2

To reduce the number of variables,a large set of variables can often be replaced by the set of cluster components.

Accepted Answer

Clustering is a technique of grouping variables based on their similarity or correlation. By using cluster components, multiple variables can be replaced by fewer variables that represent the underlying patterns in the data. This reduces the complexity of the model and makes it easier to interpret.

Question 3

In hierarchical clustering,the solution may depend on the order of cases in the data set.

Accepted Answer

Hierarchical clustering results do not depend on the order of cases in the data set because it considers all possible pair-wise distances or similarities between cases when forming clusters.

Question 4

Which method allows the researcher to obtain information on cluster membership of cases if the number of clusters is specified?

Accepted Answer

An icicle plot is a graphical method used in hierarchical clustering that allows researchers to visualize and obtain information on cluster membership of cases when the number of clusters is specified. It represents the hierarchical clustering structure and shows how clusters are formed at different levels, making it possible to identify the membership of cases in specific clusters.

Question 5

Most ________ methods are heuristics based on algorithms.

Accepted Answer

Clustering is a method in which similar items are grouped together based on certain criteria. The process of clustering involves defining a set of similarity measures and optimization algorithms. Heuristic methods are typically used in clustering algorithms to determine the optimal number of clusters or to identify the best clustering arrangement. On the other hand, factor analysis, discriminant analysis, and analysis of variance typically involve statistical modeling and hypothesis testing.

Question 6

It is helpful to profile the clusters in terms of variables that were not used for clustering.

Accepted Answer

Profiling the clusters using variables that were not used for clustering can provide additional insights into the characteristics and behavior of each cluster. This can help in identifying potential drivers of the clustering results and in making more informed decisions based on the insights gained from the profiling process.

Question 7

________ is a class of techniques used to classify objects or cases into relatively homogeneous groups.

Accepted Answer

Cluster analysis is a technique used to group objects or cases based on similarities in their characteristics. It can be used for segmentation in marketing research as well as in other fields such as biology, psychology, and social sciences. Principal components analysis, common factor analysis, and conjoint analysis are techniques used for data reduction, factor analysis, and market research, respectively, but are not specifically for grouping objects or cases.

Question 8

The ________ are the initial starting points in nonhierarchical clustering.

Accepted Answer

In nonhierarchical clustering, the initial starting points are called cluster centers, also known as seeds. These cluster centers are randomly selected from the data points in the dataset. Factor scores and factor loadings are related to factor analysis, not clustering. Cluster centroids, on the other hand, are the means of the data points within a cluster, and are not initially selected starting points.

Question 9

One method of assessing reliability and validity of clustering is to use different methods of clustering and compare the results.

Accepted Answer

It is important to use multiple clustering methods when assessing the reliability and validity of clustering. This can help to ensure that the results are consistent and accurate across different methods.

Question 10

The centroids represent the mean values of the objects contained in the cluster on each of the variables.

Accepted Answer

Centroids are calculated by taking the mean value of each variable of the objects in a cluster. Therefore, the statement is true.

Question 11

A ________ is a lower-triangle matrix containing pairwise distances between objects or cases.

Accepted Answer

A similarity/distance coefficient matrix contains pairwise distances between objects or cases, giving a measure of how dissimilar or similar they are. A classification matrix displays the predicted and actual classifications of cases, a correlation matrix shows the pairwise correlation between variables, and a factor matrix contains the factor loadings or coefficients for variables and factors in factor analysis.

Question 12

Which method of analysis does not classify variables as dependent or independent?

Accepted Answer

Cluster analysis does not classify variables as dependent or independent; instead, it groups similar observations or variables together based on their characteristics or behavior. The other methods mentioned do involve classifying variables as dependent (response) or independent (predictor) variables.

Question 13

It is possible to obtain information on cluster membership of cases via the icicle plot if the number of clusters is specified.

Accepted Answer

If the number of clusters is specified, the icicle plot can display which cases belong to each cluster, making it possible to obtain information on cluster membership.

Question 14

In non-hierarchical clustering,the F test is only descriptive.Because the cases or objects are systematically assigned to clusters to maximize differences on the clustering variables,the resulting probabilities should not be interpreted as testing the null hypothesis of no differences among clusters.

Accepted Answer

In non-hierarchical clustering, the F test is only used descriptively and the resulting probabilities should not be interpreted as testing the null hypothesis of no differences among clusters because the objects are systematically assigned to maximize cluster differences.

Question 15

Cluster analysis has been used in marketing for all of the purposes below except ________.

Accepted Answer

Cluster analysis is primarily used for grouping objects (such as customers, products, etc.) based on their characteristics or behaviors. It is not designed to directly measure the strength of relationships between variables, such as sales and advertising expenditures, which is more the domain of techniques like regression analysis.

Question 16

When cluster analysis is also used for clustering variables to identify homogeneous groups,the units used for analysis are the variables and the distance measures are computed for all pairs of variables.

Accepted Answer

When cluster analysis is used for clustering variables, the units used for analysis are the variables themselves and the distance measures are computed for all pairs of variables in order to group them into homogeneous clusters.

Question 17

Which method allows the researcher to obtain information on cluster membership of cases if the number of clusters is specified?

Accepted Answer

Dendrograms and icicle plots are graphical methods used in hierarchical clustering to show the arrangement of the clusters produced by the analysis. Both can display cluster membership of cases when the number of clusters is specified.

Question 18

Formal procedures for assessing the reliability and validity of clustering are simple and should be undertaken.

Accepted Answer

Assessing the reliability and validity of clustering is complex because it involves subjective judgment about the meaning and utility of the clusters, and there are no universally accepted criteria for determining the optimal number of clusters or the best clustering method for a given dataset.

Question 19

Principal components are usually easier to interpret than the cluster components.

Accepted Answer

Principal components are linear combinations of the original variables created in principal component analysis (PCA) to capture maximum variance, and they often do not correspond to intuitive or easily interpretable dimensions. In contrast, cluster components (or centroids in clustering analysis) represent the center of a group of similar data points, which can sometimes be more directly interpreted in terms of the original features.

Question 20

Which statement is not true about cluster analysis?

Accepted Answer

Cluster analysis is a technique for analyzing data when the criterion or dependent variable is not necessarily categorical; it can be either categorical or continuous. The independent variables can also be categorical, continuous, or a mix of both.

Quiz 20: Cluster Analysis

A(n) ________ or tree graph is a graphical device for displaying clustering results.Vertical lines represent clusters that are joined together.The position of the line on the scale indicates the distances at which clusters were joined.

To reduce the number of variables,a large set of variables can often be replaced by the set of cluster components.

In hierarchical clustering,the solution may depend on the order of cases in the data set.

Which method allows the researcher to obtain information on cluster membership of cases if the number of clusters is specified?

Most ________ methods are heuristics based on algorithms.

It is helpful to profile the clusters in terms of variables that were not used for clustering.

________ is a class of techniques used to classify objects or cases into relatively homogeneous groups.

The ________ are the initial starting points in nonhierarchical clustering.

One method of assessing reliability and validity of clustering is to use different methods of clustering and compare the results.

The centroids represent the mean values of the objects contained in the cluster on each of the variables.

A ________ is a lower-triangle matrix containing pairwise distances between objects or cases.

Which method of analysis does not classify variables as dependent or independent?

It is possible to obtain information on cluster membership of cases via the icicle plot if the number of clusters is specified.

Cluster analysis has been used in marketing for all of the purposes below except ________.

When cluster analysis is also used for clustering variables to identify homogeneous groups,the units used for analysis are the variables and the distance measures are computed for all pairs of variables.

Which method allows the researcher to obtain information on cluster membership of cases if the number of clusters is specified?

Formal procedures for assessing the reliability and validity of clustering are simple and should be undertaken.

Principal components are usually easier to interpret than the cluster components.

Which statement is not true about cluster analysis?