Sparse Principal Component Analysis (PCA)
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Questions and Answers

What is the defining characteristic of exponential growth?

  • A quantity remains constant over time
  • A quantity decreases at a rate proportional to its logarithm
  • A quantity increases at a rate proportional to its square root
  • A quantity increases at a rate proportional to its current value (correct)
  • Which model is used to capture and predict changing volition in time series data?

  • VAR
  • GARCH (correct)
  • VECM
  • ARIMA
  • What is the purpose of differencing in the ARIMA model?

  • To make the time series stationary (correct)
  • To make the time series non-stationary
  • To add trends to the time series
  • To remove trends from the time series
  • What is the primary application of Vector Auto Regression (VAR) models?

    <p>Forecasting multiple time series simultaneously</p> Signup and view all the answers

    What is Granger causality used for?

    <p>To determine if one time series can predict another</p> Signup and view all the answers

    What is the characteristic of co-integrated variables?

    <p>A linear combination of them is stationary</p> Signup and view all the answers

    What is the primary application of Vector Error Correction Model (VECM)?

    <p>Analyzing and forecasting the long-term and short-term dynamics of co-integrated variables</p> Signup and view all the answers

    What is the difference between ARIMA and ARMA models?

    <p>ARIMA is used for non-stationary time series, while ARMA is used for stationary time series</p> Signup and view all the answers

    Which model is a stochastic approach to time series modeling?

    <p>ARIMA</p> Signup and view all the answers

    What is the characteristic of exponential decay?

    <p>A quantity decreases at a rate proportional to its current value</p> Signup and view all the answers

    Study Notes

    Dimensionality Reduction

    • Sparse Principal Component Analysis (Sparse PCA) is a variant of traditional Principal Component Analysis (PCA) that introduces sparsity constraints on the principal components.
    • Sparse PCA provides a more interpretable set of principal components, performs feature selection and dimensionality reduction simultaneously, and is more efficient than regular PCA in handling high-dimensional data.
    • Factor Analysis (FA) is a statistical technique used for dimensionality reduction and exploring the underlying structure in a dataset, assuming that observed variables are influenced by latent factors.

    Clustering

    • Two-steps clustering is a clustering algorithm used to group data points into clusters based on their similarities, particularly useful for dealing with large datasets or data sets containing both categorical and continuous variables.
    • Bi-clustering, also known as block clustering or co-clustering, is a data mining technique that allows simultaneous clustering of both rows and columns of a matrix, particularly useful for identifying groups of data items that exhibit consistent patterns across both rows and columns.
    • Latent clustering, also known as Latent Class Cluster Analysis (LCCA), is a powerful technique that can uncover hidden structures in data by identifying latent subgroups or classes.
    • K-means clustering is a popular and powerful unsupervised machine learning algorithm that can be used to group data points into distinct clusters based on their similarities.

    Time Series Analysis

    • Stochastic approach is a type of time series analysis that involves modeling the future behavior of a time series as uncertain and can be modeled using probability distributions.
    • Time series decomposition is a technique used to break down a time series into its underlying component, typically trend, seasonality, and residual components.
    • Linear trend model is a deterministic approach used to identify and model trends in time series, assuming that the time series follows a straight line trend over time.
    • Exponential growth or decay models are powerful tools for analyzing and forecasting a wide range of real-world processes that exhibit proportional rates of change over time.

    Time Series Models

    • ARIMA (Autoregression Integrated Moving Average) is a stochastic approach used to model time series data, combining autoregression and moving average.
    • GARCH model (Generalized Autoregression Conditional Heteroskedasticity) is used to capture and predict changing volition in time series data.
    • VAR (Vector Auto Regression) is a multivariate time series model used to capture the linear interdependencies among multiple time series.
    • VECM (Vector Error Correction Model) is a multivariate time series model used to analyze and forecast the long-term and short-term dynamics of co-integrated variables.

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    Description

    Sparse PCA introduces sparsity constraints on principal components, finding sparse linear combinations of original features, useful in high-dimensional data scenarios.

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