Which statistical measure indicates the strength and direction of a relationship?

The correlation coefficient is a statistical measure that quantifies the degree to which two variables are related, providing both the strength and direction of that relationship. It ranges from -1 to +1, where a value closer to +1 indicates a strong positive relationship (as one variable increases, the other also increases), a value closer to -1 indicates a strong negative relationship (as one variable increases, the other decreases), and a value around 0 suggests no linear relationship between the variables. This capability makes the correlation coefficient especially useful in various fields, including psychology, where understanding relationships between different psychological constructs can inform research and interventions.

The other options serve different purposes: the mean is a measure of central tendency, representing the average value of a dataset, while the median identifies the middle value when a dataset is ordered. The standard deviation measures the variability or dispersion in a dataset, indicating how much individual scores differ from the mean. Each of these measures provides valuable information, but they do not convey the strength and direction of relationships between variables.