Resemblance profiles as clustering decision criteria: Estimating statistical power, error, and correspondence for a hypothesis test for multivariate structure
Abstract:Clustering data continues to be a highly active area of data analysis, and resemblance profiles are being incorporated into ecological methodologies as a hypothesis testing‐based approach to clustering multivariate data. However, these new clustering techniques have not been rigorously tested to determine the performance variability based on the algorithm's assumptions or any underlying data structures. Here, we use simulation studies to estimate the statistical error rates for the hypothesis test for multivar… Show more
“…Given the problems associated with the dreaded duality, it might seem surprising that these tests are quickly gaining popularity in the field of ecology (Kilborn et al , 2017). It turns out that these issues are not terribly relevant in that field.…”
Purpose
Strategic groups research has been hampered by the poor alignment between theory and methods. This has been due in large part to the lack of significance tests for cluster analysis. Now that significance tests are available, the theoretical and methodological implications are discussed. The paper aims to discuss these issues.
Design/methodology/approach
The theory behind strategic groups is reframed to capitalize on the available significance tests. Subsequently, the significance tests are also modified to fit the proposed theory. Due to this integrative approach, this is both a theoretical and a methodological paper.
Findings
In lieu of significance tests, finding differences in performance emerged as the litmus test for the existence of discrete strategic groups. The concept of strategic groups gradually evolved to fit this requirement. Now that significance tests are available, these legacy effects of the structure-performance link can be removed. This reveals that three conflicting concepts have been sharing the label of strategic groups: strategic categories, interdependent strategic groups and strategic performance groups. The theory also reveals that the significance tests developed in ecological research need modifications for use in strategic groups research.
Research limitations/implications
A theory is proposed for interdependent strategic groups and a significance test of external isolation is proposed as part of this integrative solution.
Originality/value
This integrative solution appears to resolve the historical mismatch between theory and methods that has plagued this field since its inception. This creates a variety of intriguing areas for future research.
“…Given the problems associated with the dreaded duality, it might seem surprising that these tests are quickly gaining popularity in the field of ecology (Kilborn et al , 2017). It turns out that these issues are not terribly relevant in that field.…”
Purpose
Strategic groups research has been hampered by the poor alignment between theory and methods. This has been due in large part to the lack of significance tests for cluster analysis. Now that significance tests are available, the theoretical and methodological implications are discussed. The paper aims to discuss these issues.
Design/methodology/approach
The theory behind strategic groups is reframed to capitalize on the available significance tests. Subsequently, the significance tests are also modified to fit the proposed theory. Due to this integrative approach, this is both a theoretical and a methodological paper.
Findings
In lieu of significance tests, finding differences in performance emerged as the litmus test for the existence of discrete strategic groups. The concept of strategic groups gradually evolved to fit this requirement. Now that significance tests are available, these legacy effects of the structure-performance link can be removed. This reveals that three conflicting concepts have been sharing the label of strategic groups: strategic categories, interdependent strategic groups and strategic performance groups. The theory also reveals that the significance tests developed in ecological research need modifications for use in strategic groups research.
Research limitations/implications
A theory is proposed for interdependent strategic groups and a significance test of external isolation is proposed as part of this integrative solution.
Originality/value
This integrative solution appears to resolve the historical mismatch between theory and methods that has plagued this field since its inception. This creates a variety of intriguing areas for future research.
“…, Kilborn et al. ). This form of clustering, referred to as SIMPROF clustering hereafter, assesses H o2 = “there is no multivariate structure among objects (years) with respect to the set of descriptors (Y).” The method was developed as a form of hypothesis testing‐based clustering (Clarke et al.…”
Section: Methodsmentioning
confidence: 99%
“…) and is well suited for high‐dimensional, continuous datasets with relatively large sample sizes (Kilborn et al. ). The assessment of H o2 was made at all possible levels of resemblance identified by an UPGMA clustering solution produced from a Euclidean resemblance matrix (Y Euc ; Legendre and Legendre ).…”
Integrated ecosystem assessment provides a practical framework for implementing ecosystem‐based fisheries management (EBFM) while also balancing socioeconomic and ecological objectives. However, significant challenges remain, including (1) the identification of relevant ecosystem‐level fisheries management indicators; (2) quantitatively describing the historical qualitative changes to fisheries ecosystem resource organization; (3) elucidating dynamic system regimes and their trade‐offs related to variability in both natural and anthropogenic drivers; and (4) distilling and communicating the results to stakeholders and managers. Here, we describe the Ecosystem‐Level, Management‐Indicator Selection Tool (EL‐MIST), which was developed to address these EBFM challenges. We also present a case study from the Gulf of Mexico large marine ecosystem (Gulf LME) where EL‐MIST was applied to 79 time series indicators from the Gulf's 2013 ecosystem status report for the period 1980–2011. Results from Gulf LME's EL‐MIST model indicated that the functional response of the Gulf's fisheries resources underwent significant reorganizations during the study period, primarily driven by basin‐scale climate variability and shifting fishing fleets’ targets, effort, and associated regulatory environments, over time. Using EL‐MIST, we identified four unique organizational regimes, and we were able to describe the prominent differences in the underlying resources’ structure and function between those dynamic regimes. We also detail three pertinent ecological regime shifts over the 30‐yr study period and present evidence for the dominating effects of commercial and recreational fishing activities, along with the Atlantic Multidecadal Oscillation and its teleconnected processes, on the organization of fisheries resources. Support for the hypothesis that fishing intensity can affect the relative resilience of a fishery ecosystem that is undergoing climatic and physical–chemical environmental changes is also presented here, as are results implicating a slowing trend in the rates of change across many relevant ecosystem‐level fisheries‐management indicators. When implementing EBFM, the EL‐MIST protocol is useful for distilling the large amounts of information gathered by large‐scale monitoring efforts and assessments. This new framework is transferable across management systems, is ideal for use with current indices and metrics, has the flexibility to address a wide range of inquiries, and can help disentangle complex fisheries ecosystem dynamics to help better inform management recommendations.
“…Egg abundance was square root transformed, and Bray-Curtis similarity was calculated for all possible station pairs. Cluster analysis was performed using these Bray-Curtis similarities, and a similarity profile analysis (SIMPROF) was used to identify statistically significant groupings of stations within the results of the cluster analysis (Kilborn et al, 2017). A seriated heatmap was generated to allow simultaneous visual comparisons of (1) station compositional similarity and (2) species associations.…”
To help determine whether planktonic eggs of fishes on the West Florida Shelf (WFS) are retained locally or exported elsewhere, we collected fish eggs by plankton net from 17 locations (stations) and identified them using DNA barcoding. We then entered the station coordinates into the West Florida Coastal Ocean Model (WFCOM) and simulated the trajectories of the passively drifting eggs over 2 weeks at three depths (surface, midwater, and near bottom). The results indicated there were two groups of trajectories: a nearshore group that tended to be retained and an offshore group that tended toward export and potential long‐distance dispersal. We also found evidence of a relationship between retention and higher fish‐egg abundance; nearshore stations were associated with higher fish‐egg abundances and higher retention. We suggest this is the result of (1) increased spawning in high‐retention areas, (2) increased drift convergence in high‐retention areas, or both processes acting together. Community analysis using SIMPROF indicated the presence of a depth‐related (retention‐related) difference in species assemblages. Fish‐egg species were also categorized as pelagics or non‐pelagics; there was no evidence of pelagic species being more likely to be exported.
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