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Cluster Interpretation: Dynamic Profile

Background & Context

MaleClusters.xbl

Dynamic Profile for Cluster Interpretation

  • We can use BayesiaLab’s optimization tools to work with more complex sets of evidence. One of these optimization tools is the Dynamic Profile.
  • The Dynamic Profile uses a greedy search algorithm to simulate sets of evidence that maximize the probability of Cluster 3\mathit{Cluster\ 3}.
  • It may seem counterintuitive to think of optimizing evidence to achieve membership in Cluster 3\mathit{Cluster\ 3}. After all, we cannot modify body measurements.
  • However, we can think of those characteristics that assign a subject to Cluster 3\mathit{Cluster\ 3} most quickly as prototypical traits of Cluster 3\mathit{Cluster\ 3}.
  • To start Dynamic Profile, select Main Menu > Analysis > Target Optimization > Dynamic Profile.
  • In the Dynamic Profile Settings, we need to specify that we want to maximize the probability of Cluster 3\mathit{Cluster\ 3} by searching across Hard Evidence.
DynamicProfileSettings
  • Clicking OK starts the search and quickly produces a solutions table, which opens in a new window:
DynamicProfileReport
  • The starting point is the row in the table marked A priori, which shows that P(Factor0=C3)=12.955%P(\mathit{Factor}_0=\mathit{C3})=12.955\%, i.e., the marginal probability of C3\mathit{C3}.
  • If we evaluate the hypothesis 3Bicep Girth>363 - \mathit{Bicep\ Girth} \gt 36, the posterior probability increases, i.e., P(Factor0=C33Bicep Girth>36)=41.096%P(\mathit{Factor}_0=\mathit{C3} \mid 3 - \mathit{Bicep\ Girth} \gt 36)=41.096\%.
  • In this case, the Bayes Factor is 3.172, meaning that with this hypothesis, C3\mathit{C3} membership is 3.172 times more probable than without it.
  • Setting 7Hip Girth101.87 - \mathit{Hip\ Girth} \le 101.8, the probability of C3\mathit{C3} membership increases further to 72.938%.
  • With 4Navel Girth85.24 - \mathit{Navel\ Girth} \le 85.2 and 6Forearm Girth>29.46 - \mathit{Forearm\ Girth} \gt 29.4, we reach a C3\mathit{C3} probability of 100%.
  • As a result, we can interpret this set of evidence as a prototypical profile for a subject in C3\mathit{C3}:
    • 3Bicep Girth>363 - \mathit{Bicep\ Girth} \gt 36
    • 7Hip Girth101.87 - \mathit{Hip\ Girth} \le 101.8
    • 4Navel Girth85.24 - \mathit{Navel\ Girth} \le 85.2
    • 6Forearm Girth>29.46 - \mathit{Forearm\ Girth} \gt 29.4