Positive Correlation in Psychology: Examples & Definition

Explore the characteristics of positive correlations. Learn about strength and direction, the difference between positive and negative correlations, and more.
What Is a Positive Correlation?
Imagine that you are conducting research on school achievement. You want to know if a relationship exists between school achievement and attendance. You collect the grade point average (GPA) and days present during the school year from 15 high school students. Your findings are reported in this table:

Data table for example
Student data
If you look at the data closely, you will begin to notice that as the days present increases, GPA also increases. In other words, there is a positive correlation between school achievement and attendance.

What does it mean when we say two variables are correlated with each other? It means that two variables have a relationship between them. A correlation is a single numerical value that is used to describe the relationship. Correlation is most commonly measured by the Pearson Product Moment Correlation, which is commonly referred to as Pearson’s r. Because of this, a correlation is usually represented by the letter r.

Every correlation has two qualities: strength and direction. The direction of a correlation is either positive or negative. In a negative correlation, the variables move in inverse, or opposite, directions. In other words, as one variable increases, the other variable decreases. For example, there is a negative correlation between self-esteem and depression. In other words, the higher your self-esteem, the lower your feelings of depression.

When two variables have a positive correlation, it means the variables move in the same direction. This means that as one variable increases, so does the other one. In the example above, we noted that the students who attended school more frequently had the highest GPAs. As the days present at school decreased, so did the GPA.

Some other examples of variables that have a positive correlation are:

GPA and SAT score: The students with the higher GPAs are usually the ones who perform best on the SAT.
Education and salary: The more years of schooling you have, the higher your income will likely be.
Depression and suicide: Those who suffer from depression tend to have higher rates of suicide than those who do not.
Strength of a Correlation
We determine the strength of a relationship between two correlated variables by looking at the numbers. A correlation of 0 means that no relationship exists between the two variables, whereas a correlation of 1 indicates a perfect positive relationship. It is uncommon to find a perfect positive relationship in the real world. Chances are that if you find a positive correlation between two variables that the correlation will lie somewhere between 0 and 1.

The further away from 1 that a positive correlation lies, the weaker the correlation. Similarly, the further a negative correlation lies from -1, the weaker the correlation. A correlation of 0.5 is not stronger than a correlation of 0.8. A correlation of -0.5 is not stronger than a correlation of -0.8.

Two correlations with the same numerical value have the same strength whether or not the correlation is positive or negative. This means that a correlation of -0.8 has the same strength as a correlation of 0.8.

The following guidelines are useful when determining the strength of a positive correlation:

1: perfect positive correlation
.70 to .99: very strong positive relationship
.40 to .69: strong positive relationship
.30 to .39: moderate positive relationship
.20 to .29: weak positive relationship
.01 to .19: no or negligible relationship
0: no relationship exists