What does the Pearson product moment correlation coefficient measure?

Question

Options

• Anonlinear and nonmonotonic association between two variables
• Blinear and monotonic association between two variables
• Clinear and nonmonotonic association between two variables
• Dnonlinear and monotonic association between two variables

• A
  6% (1)
• B
  89% (16)
• D
  6% (1)

Explanation

Pearson's r measures the strength and direction of a linear relationship between two continuous variables, and because a perfectly linear relationship is also monotonic (consistently increasing or decreasing), it is both linear and monotonic - making B correct. Option A is wrong on both counts: Pearson's r cannot detect nonlinear or nonmonotonic patterns (e.g., a U-shaped curve would yield r ≈ 0 even with a strong relationship). Option C is wrong because "nonmonotonic" implies a relationship that reverses direction, which Pearson's r is blind to. Option D is wrong because Pearson's r requires linearity - Spearman's rho handles nonlinear but monotonic associations. Memory tip: Think "Pearson = Perfect line" - it only captures straight-line trends, and a straight line always goes consistently one direction (monotonic).

No community discussion yet for this question.