What does the correlation coefficient indicate?

The correlation coefficient is a statistical measure that quantifies the degree to which two variables are related. It provides two key pieces of information: the strength of the relationship and the direction. A positive correlation coefficient indicates that as one variable increases, the other variable also tends to increase, while a negative correlation coefficient signifies that as one variable increases, the other tends to decrease. The value of the correlation coefficient ranges from -1 to +1, where values closer to +1 or -1 indicate a stronger relationship between the variables, and values close to 0 suggest little to no relationship. This understanding of the relationship's strength and direction makes the correlation coefficient a crucial tool in developmental psychology and other fields, allowing researchers to identify and interpret patterns in data.

In contrast, the other options do not accurately represent the function of the correlation coefficient. It does not indicate causation (the second option), nor does it assess the reliability of measurements (the third option), and it is unrelated to qualitative research quality (the fourth option). Each of these aspects, while important in research, pertains to different statistical concepts or methodologies that do not directly overlap with the purpose of the correlation coefficient.