To estimate the best correlation coefficient, we need to understand the sign and strength of the relationship between two variables.
- A correlation coefficient of 1 indicates a perfect positive linear relationship.
- A coefficient of 0.98 suggests a very strong positive linear relationship.
- A coefficient of 0.75 indicates a moderate to strong positive relationship.
- A coefficient of -0.98 shows a very strong negative linear relationship.
Without additional context or data, it's difficult to choose definitively. However, if you're looking for a strong positive correlation, 0.98 would generally be considered the best estimated correlation coefficient among the choices provided. If the relationship is negative but very strong, then -0.98 would be the best choice.
If I were to choose based on the common context of relationships typically being positive in nature unless otherwise stated, I would select 0.98.