Predictive and Specialized Modeling • Association Analysis • Association Analysis Platform Options • Rotated SVD
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Rotated SVD
(Available only when SVD is selected from the red triangle menu next to Association Analysis.) The Rotated SVD option performs a varimax rotation on the singular value decomposition (SVD) of the transaction item matrix. See Transaction Item Matrix. You must specify a number of rotated singular vectors, which corresponds to the number of topics that you want to retain from the transaction item matrix. After you specify a number of topics, the Topic Terms and Topic Scores Plots reports appear. Topic analysis is equivalent to a rotated principal components analysis (rotated PCA).
Topics are groups of transactions that are grouped based on a primary item indicator, as well as secondary item indicators. For each topic, every item has a weight that influences a transaction’s membership in the topic. The cumulative sum of the item weights for all of the items that are present in a transaction is called the topic score. Topic scores reflect the strength of a transaction’s membership for a topic.
The varimax rotation rotates the singular vectors to more closely align them with the coordinate axes. This rotation helps facilitate interpretation by resulting in high loadings on a few axes and small loadings on the others. The loadings are given in the Rotated V Matrix and Rotated U Matrix reports.
See Additional Example: SVD Analysis.
Topic Items Report
(Available only when Rotated SVD is selected from the red triangle menu next to Association Analysis.) The Topic Items report shows the items that have the largest loadings in each topic after rotation. There are additional reports that show the components of the rotated singular value decomposition.
The report shows a table of items for each topic. The items in each table are the ones that have the largest loadings in absolute value for each topic. Each table is sorted in descending order by the absolute value of the loading. These tables can be used to determine conceptual themes that correspond to each topic.
The Topic Items report also contains the following matrix reports:
Variance Explained by Each Topic
Contains a table of the variance explained by each topic. The table also contains columns for the percent and cumulative percent of the variation explained by each topic.
Term Topic Loadings
Contains a matrix of the loadings across topics for each item. This matrix is equivalent to the transpose of the factor loading matrix in a rotated PCA.
Document Topic Scores
Contains a matrix of transaction scores for each topic. Transactions with higher scores in a topic are more likely to be associated with that topic.
Rotation Matrix
Contains the rotation matrix for the varimax rotation.
See Additional Example: SVD Analysis.
Topic Scores Plots Report
(Available only when Rotated SVD is selected from the red triangle menu next to Association Analysis.) The Topic Scores Plots report is a visual representation of the matrix in the Document Topic Scores report. Each panel in the plot corresponds to one of the topics, or one of the rows of the Document Topic Scores matrix. Within each panel, each point corresponds to one of the transactions in the data table, or one of the columns of the transaction item matrix. See Additional Example: SVD Analysis.

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Help created on 9/19/2017