Which correlation is the strongest?

JODHPUR AIIMS SNO-2018

Nursing Research & Statistics

Medium

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

The correlation coefficient (r) ranges from -1.00 to +1.00.
The strength of a correlation is determined by its absolute value (how far it is from 0), not its sign (+ or -).
A value of -1.00 has an absolute value of 1.00, which is the highest possible value, representing a perfect correlation.
Therefore, -1.00 is the strongest correlation among the given options.

Option A: A correlation of +0.90 is a strong positive correlation, but its absolute value (0.90) is less than the absolute value of -1.00 (1.00).
Option B: A correlation of -0.95 is a very strong negative correlation, but its absolute value (0.95) is less than the absolute value of -1.00 (1.00).
Option C: A correlation of +0.10 indicates a very weak positive relationship. Its absolute value (0.10) is the closest to zero among the options, making it the weakest correlation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Strength and direction of correlation coefficients as background academic context rather than a clinical decision trigger.
In nursing research, understanding correlation is crucial for interpreting studies that examine relationships between variables, such as the link between a specific nursing intervention and patient outcomes (e.g., patient satisfaction, recovery time).
A nurse might read a study showing a strong negative correlation (e.g., r = -0.85) between hours of patient education and rates of post-discharge complications. This indicates that more education is associated with fewer complications, guiding evidence-based practice.
What if? If a study found a correlation of r = +0.20 between nurse staffing levels and patient falls, it would suggest a very weak positive relationship. This means that as staffing increases, falls slightly increase, but the link is so weak it's likely not clinically significant and may be due to other confounding factors (e.g., higher acuity patients on more staffed units).

How to Approach the Question

Identify the core question: The question asks to find the 'strongest' correlation.
Recall the key principle of correlation strength: Strength is measured by the absolute value of the correlation coefficient (r), which is its distance from zero, regardless of the sign.
Convert each option to its absolute value: |+0.90| = 0.90; |-0.95| = 0.95; |+0.10| = 0.10; |-1.00| = 1.00.
Compare the absolute values: Compare 0.90, 0.95, 0.10, and 1.00.
Select the largest absolute value: 1.00 is the largest value, which corresponds to the option -1.00.
Conclude that -1.00 represents the strongest possible correlation.

Concept Tested & Keywords

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