Final answer:
The observation that adults who are more optimistic have a higher level of life satisfaction represents a positive correlation as both levels rise in tandem. This is opposed to a negative correlation where variables move in opposite directions. The strength of the correlation is indicated by the correlation coefficient, with values close to 0 representing a weaker relationship.
Step-by-step explanation:
A researcher has observed that adults who are more optimistic tend to have a higher level of life satisfaction than adults who are less optimistic. This is an example of a positive correlation. A positive correlation means that as one variable increases, the other variable also tends to increase. In this case, as the level of optimism goes up, so does the life satisfaction. This is opposite to a negative correlation, where an increase in one variable would result in a decrease in the other. An example of negative correlation could be the relationship between the amount of sleep one gets and their level of tiredness during the day, with more sleep being associated with less tiredness.
It is important to remember that a positive correlation does not always mean that there is a causal relationship or that the variable under investigation has health benefits. The correlation coefficient, which measures the strength and direction of the relationship, indicates the weakest relationship when it is closest to 0. In contrast, for example, a coefficient of -0.90 indicates a stronger negative relationship than a coefficient of -0.50.