A study finds a Spearman rank correlation coefficient of -0.82 between maternal education level (graded I to V) and number of under-five diarrhoea episodes per year. The correct interpretation is:
- A Weak negative linear relationship between the two variables
- B Education causes an 82 percent reduction in diarrhoea episodes
- C Strong negative monotonic relationship between the two variables ✓
- D Strong positive relationship, since the absolute value exceeds 0.8
Correct answer: C. Strong negative monotonic relationship between the two variables
Explanation
Spearman correlation measures the strength and direction of a monotonic relationship using ranked data and ranges from -1 to +1. A value of -0.82 indicates a strong negative monotonic association: higher education grades go with fewer episodes. Correlation never establishes causation, so option B overstates the finding, and the sign determines direction, so the negative value rules out a positive relationship.
Reference: Mahajan's Methods in Biostatistics for Medical Students, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.