Principal component analysis: a review and recent developments

Jolliffe, Ian T.; Cadima, Jorge

doi:10.1098/rsta.2015.0202

Cited by 5,284 publications

(3,686 citation statements)

References 46 publications

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“…The chemico-physical included parameters, measured before the experiment on lake water samples, were: total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TP), nitrate nitrogen (NO 3 − ), ammonium nitrogen (NH 4 + ), temperature (TEMP), alkalinity (ALK), and pH. All data were centered (mean value = 0) and scaled (variance = 1) to allow comparison among parameters [39]. Only six predictors were selected from the initial set of 8 to perform the following analyses.…”

Section: Data Analysesmentioning

confidence: 99%

Ammonium Transformation in 14 Lakes along a Trophic Gradient

Leoni

Patelli

Soler

et al. 2018

Water

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Ammonia is a widespread pollutant in aquatic ecosystems originating directly and indirectly from human activities, which can strongly affect the structure and functioning of the aquatic foodweb. The biological oxidation of NH 4 + to nitrite, and then nitrate is a key part of the complex nitrogen cycle and a fundamental process in aquatic environments, having a profound influence on ecosystem stability and functionality. Environmental studies have shown that our current knowledge of physical and chemical factors that control this process and the abundance and function of involved microorganisms are not entirely understood. In this paper, the efficiency and the transformation velocity of ammonium into oxidised compounds in 14 south-alpine lakes in northern Italy, with a similar origin, but different trophic levels, are compared with lab-scale experimentations (20 • C, dark, oxygen saturation) that are performed in artificial microcosms (4 L). The water samples were collected in different months to highlight the possible effect of seasonality on the development of the ammonium oxidation process. In four-liter microcosms, concentrations were increased by 1 mg/L NH 4 + and the process of ammonium oxidation was constantly monitored. The time elapsed for the decrease of 25% and 95% of the initial ion ammonium concentration and the rate for that ammonium oxidation were evaluated. Principal Component Analysis and General Linear Model, performed on 56 observations and several chemical and physical parameters, highlighted the important roles of total phosphorus and nitrogen concentrations on the commencement of the oxidation process. Meanwhile, the natural concentration of ammonium influenced the rate of nitrification (µg NH 4 + /L day). Seasonality did not seem to significantly affect the ammonium transformation. The results highlight the different vulnerabilities of lakes with different trophic statuses.

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Section: Data Analysesmentioning

confidence: 99%

Ammonium Transformation in 14 Lakes along a Trophic Gradient

Leoni

Patelli

Soler

et al. 2018

Water

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“…3). A PCA is considered a robust analysis for use of categorical data with large datasets (Jolliffe and Cadima, 2016). Consequently, PCAs accommodate data measured at different scales with multiple interactions.…”

Section: Resultsmentioning

confidence: 99%

Sustainable financing of a national Marine Protected Area network in Fiji

Ison

Hills

Morris

et al. 2018

Ocean & Coastal Management

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“…PCA is one of the most widespread dimension reduction methods going back to research of Pearson (1901) and Hotelling (1933). For a brief introduction to PCA, please see, e.g., Jolliffe and Cadima (2016) …”

Section: Principal Component Analysis 315mentioning

confidence: 99%

Detecting dominant changes in irregularly sampled multivariate water quality data sets

Lehr¹,

Dannowski²,

Kalettka³

et al. 2018

Preprint

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Time series of catchment water quality often exhibit substantial temporal and spatial variability which can rarely be traced back to single causal factors. Numerous anthropogenic and natural drivers influence groundwater and stream water quality, 20 especially in regions with high land use intensity. In addition, typical existing monitoring data sets, e.g. from environmental agencies, are usually characterized by relatively low sampling frequency and irregular sampling in space and / or time. This complicates the differentiation between anthropogenic influence and natural variability as well as the detection of changes in water quality which indicate changes 25 of single drivers. Detecting such changes is of fundamental interest for water management purposes as well as for scientific analyses.We suggest the new term 'dominant changes' for changes in multivariate water quality data that concern 1) more than a single variable, 2) more than one single site and 3) more than short-term fluctuations or single events and present an exploratory 30 framework for the detection of such 'dominant changes' in multivariate water quality data sets with irregular sampling in space and time. Firstly, we used a non-linear dimension reduction technique to derive multivariate water quality components. The components provide a sparse description of the dominant spatiotemporal dynamics in the multivariate water quality data set. In addition, they can be used to derive 35 hypotheses on the dominant drivers influencing water quality. Secondly, different sampling sites were compared with respect to median component values. Thirdly, time series of the components at single sites were analysed for seasonal patterns and linear and non-linear trends. Spatial and temporal heterogeneities are efficiently used as a source of information rather than being considered as noise. Besides, non-40 linearities are considered explicitly. The approach is especially recommended for the exploratory assessment of existing long term low frequency multivariate water quality monitoring data.

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Principal component analysis: a review and recent developments

Abstract: One contribution of 13 to a theme issue 'Adaptive data analysis: theory and applications' .

Cited by 5,284 publications

References 46 publications

Ammonium Transformation in 14 Lakes along a Trophic Gradient

Ammonium Transformation in 14 Lakes along a Trophic Gradient

Sustainable financing of a national Marine Protected Area network in Fiji

Detecting dominant changes in irregularly sampled multivariate water quality data sets

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