Mathematics / Statistics

Multivariate Analysis Quiz

Many variables at once.

Answer five questions about Multivariate Analysis and get instant feedback.

Question 1

Hidden factor that helps explain observed measurements

Answer options

  • Latent variable
  • Observed variable
  • Sample statistic
  • Random error

Key Idea

In psychology, traits like "intelligence" are treated as latent variables: you cannot measure them directly, but they reveal themselves through patterns across many test questions.

Question 2

What predicts which category a new case belongs to?

Answer options

  • Classification
  • Clustering
  • Regression
  • Sampling

Key Idea

Many classifiers output class probabilities, not just labels, so you can tune a decision threshold to trade off false alarms versus missed cases depending on what matters most.

Question 3

What can change a lot when the chosen distance or similarity measure changes?

Answer options

  • Clustering results
  • Regression slopes
  • Confidence intervals
  • Sample size

Key Idea

Switching from Euclidean to cosine distance can flip clusters from grouping by magnitude to grouping by direction, so the same data can yield totally different "natural" groupings.

Question 4

This image question appears in the interactive quiz.

Answer options

  • Confusion matrix
  • Box plot
  • Residual plot
  • Decision boundary

Key Idea

A confusion matrix separates correct classifications from specific types of mistakes.

Question 5

What matrix equals a covariance matrix after each variable is standardized to mean $0$ and variance $?

Answer options

  • Correlation matrix
  • Covariance matrix
  • Kernel matrix
  • Design matrix

Key Idea

Because the correlation matrix is scale-free, PCA on standardized data is equivalent to eigen-decomposing it, and its off-diagonals are exactly the cosines of angles between centered variable vectors.

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