Data Pre-processing Techniques in Data Mining

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Questions and Answers

Which method replaces data with a smaller representation, such as parameters using parametric methods like regression models?

  • Singular Value Decomposition (SVD)
  • Aggregates
  • Wavelet transform
  • Regression models (correct)

What technique helps obtain a compressed representation of the original data by reducing the dimensionality of a dataset?

  • Standardising
  • Discretisation
  • Normalisation
  • Principal Component Analysis (PCA) (correct)

What is the main purpose of feature selection in data pre-processing?

  • To increase dimensionality
  • To decrease data accuracy
  • To introduce redundancy
  • To eliminate redundant features (correct)

Which approach to feature selection selects features before running the data mining algorithm using an approach independent of the task?

<p>Filter approaches (A)</p> Signup and view all the answers

Which method uses the target data mining algorithm as a black box to find the best subset of attributes for feature selection?

<p>CART (D)</p> Signup and view all the answers

Why do data mining algorithms usually work better if the dimensionality of the data is lower?

<p>To reduce noise and improve efficiency (A)</p> Signup and view all the answers

What is the purpose of standardisation in data pre-processing?

<p>To transform the data to fall within specific ranges (D)</p> Signup and view all the answers

In data transformations, what is the main reason for applying normalisation?

<p>To put data on a common scale like [-1, 1] or [0, 1] (C)</p> Signup and view all the answers

Why is it important to put variables on similar scales during data pre-processing?

<p>To prevent bias due to measurement units affecting the results (A)</p> Signup and view all the answers

What is the reason for removing size effects and giving all variables equal weight during transformations?

<p>To ensure all variables have an equal impact on the analysis (B)</p> Signup and view all the answers

Which transformation technique helps to maintain the validity of results while making them more useful?

<p>Discretization (C)</p> Signup and view all the answers

How can different measurement units impact data analysis according to the text?

<p>They can cause different outcomes in the analysis due to variable scales (B)</p> Signup and view all the answers

What is the primary purpose of transforming variables by centring?

<p>To put variables on similar scales (D)</p> Signup and view all the answers

When normalising data for methods like Neural network and Clustering, what is a key reason for this transformation?

<p>To achieve homogeneity of data (C)</p> Signup and view all the answers

Which statement best describes why mathematical transformations are used?

<p>To improve the interpretability of variable scales (B)</p> Signup and view all the answers

In the context of reasons for mathematical transformations, what does it mean to 'improve homogeneity of data'?

<p>Creating consistency in the data spread (C)</p> Signup and view all the answers

When considering data transformation, what should be done if it is not necessary to transform the data?

<p>Avoid transforming the data unnecessarily (C)</p> Signup and view all the answers

What is suggested as a better alternative to arbitrary and uninterpretable results when transforming data?

<p>Employing non-parametric methods instead (A)</p> Signup and view all the answers

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