01.04 Correlation: Is it a coincidence?
The invalid assumption that the correlation implies cause is probably among the two or three most serious errors of human reasoning.
~Stephen Jay Gould (1941–2002) American Paleontologist and Evolutionary Biologist
Correlation:Relationship between two variables.
Causation:The causal relationship; one factor actually caused the next factor.
The strength of the relationship between one factor and another can be explained as a correlation. Scientists have linked childhood obesity with television watching. This can be explained by a couple of reasons. One is children who are overweight may be too tired and not motivated enough to do more than watch television. Another may be television watching results in less exercise thereby causing overweight children. Does television watching cause overweight children? Absolutely not! So we can conclude there is a correlation not a causationin childhood obesity and television watching.
Objectives: After completing this lesson, you will be able to:
- Examine how correlation is used in psychology.
- Identify examples of correlations.
01.04 Correlation: Is it a coincidence?
Phenomenon: An unusual, significant, or unaccountable fact or occurrence.
Often we read scientific reports claiming that one variable can predict another variable. We are led to believe that if we do something, something else will happen. What about the other factors we must consider? There are reasons why phenomenon occur. This is another time when thinking critically is important to understand why behavior can be linked to a variable.
We study correlations in psychology to gain a better understanding of two objects or events occurring together that seem like causation but can actually be a coincidence. The word correlation can be looked at like this: "co-relation" meaning the same thing as "coincidence" or things occurring together. Correlations are very important, because they allow prediction. However, a correlation does not tell you about causality. In short, when we have no theory to explain behavior, we look to correlations to explain the event.
Correlations
Illusory Correlation:The perception of a relationship between two variables that does not exist
Recall:A measure of memory where a person must remember the information; for example: a fill in the blank test.
Correlations make visible the relationships we might otherwise miss. There are also correlations about relationships that actually do not exist. A perceived nonexistent correlation is an illusorycorrelation. When we believe there is a correlation between two things, we are likely to notice and recallinstances that confirm our belief. For example, a high-school athlete wears a certain pair of socks and the team wins. This athlete continues to wear these socks as his/her belief is the socks are what caused the team to win. Illusory correlations help explain the superstitious beliefs. Because we are sensitive to dramatic or unusual events, we are especially likely to notice and remember the occurrence of two such events that happen sequentially. For example, a premonition that a friend would call after you drink three sips of water. When the friend calls we are convinced this was due to the ritual and premonition. However, when the friend calls and you have not had premonition, we are less likely to remember the nonevent.
Correlations show relationships between variables. Showing that two variables are related does not justify claiming that a causal relationship exists. In all instances, there are other explanations as to why this relationship between the two variables exists. To determine whether a correlation is negative or positive, we must look at the relationship between the two factors. To help us determine if the relationship is positive or negative, we go back to the mathematical rule for multiplying integers.
Values / Equals / See the MathTwo Positives / Positive / + times + = +
Two Negatives / Positive / - times - = +
A Positive and a Negative / Negative / + times - = -
These rules also hold true in psychology. The only difference is we often deal with words instead of numbers in psychology. Below are some examples of positive and negative words.
Positive Words / Negative WordsMore / Less
Better / Worse
Greater / Lower
Increase / Decrease
Longer / Shorter
Similar / Dissimilar
The point is this—just because there is a correlation between two things does not imply that one thing caused the other. Let’s take a look...
A study of married couples showed that the longer they have been married the more similar their opinions on political views. Is this relationship positive or negative? The words we are looking at for comparison are "longer" and "similar" and both are positive words. Since two positives equal a positive we know this is a positive correlation. Two factors of why this may be true would be: They may have had similar life experiences and since they have been married for so long, they have had an influence on one another’s political views. It is important to remember that just because there is a correlation between two things this does not mean that one thing caused the other.
An intelligence test was given to children in an orphanage. The results showed that the longer the children have lived in the orphanage, the lower the child’s score. Would this be a negative correlation or a positive correlation? The words we are looking at for comparison are "longer" and "lower." Since "longer" is positive and "lower" is negative, we can deduce this is a negative correlation. Two possible explanations could be: the environment has had an adverse effect on the cognitive ability of the child and that children who are considered "intelligent" are more likely to be adopted. Again, we are reminded that just because there is a correlation between two things does not imply one thing caused the other.
To help you determine if a correlation is positive or negative, you will need the help of your two thumbs. Let's try it: the more time (put your right thumb up) kids spend on the street the higher (put your left thumb up) the higher the crime rate. Look at your thumbs. Now look at the Rules of Integers. This is a positive correlation—not because it is a good thing, but because the crime rate is higher when kids spend more time on the streets.
Can you think of correlations to your life? Let’s look at two more examples:
Gina, a high school sophomore, had a crush on Peter, a high school senior. She was trying to get him to take her to prom. Her friend, Betty, noticed that the more Gina called, texted, and instant messaged Peter, the less he spoke to Gina in school. This would be a negative correlation as the word "more" is positive and the word "less" is negative. Two possible explanations could be: Peter had less to say to Gina as they spoke via phone, instant messenger, and by text and Peter felt smothered by Gina’s attempts to contact him so much.
Anthony, a high school athlete, wanted to play first string quarterback for the big Friday night game. Anthony’s mom pointed out that the more time Anthony spent in the gym, the more playing time he was given during the game. This would be a positive correlation as the word "more" is positive. Two possible explanations would be: Anthony’s coach saw how hard he was trying by being in the gym and Anthony’s workouts were making him stronger and a better player.
In the above examples, there are many more explanations as to the causal relationship between the variables. The point is this—just because there is a correlation between two things does not imply that one thing caused the other.
+word PLUS+word =+correlation (more, higher, biggest, best, most, etc.)
-word PLUS -word =+correlation (less, none, lower, fewest, slower, worse, etc.)
-word PLUS+word =-correlation
+word PLUS -word =-correlation
The more… the higher +
The slower… the worse +
The more… the fewer -
The less…. The greater -
Assessment: 01.04 Correlation – Exam
1.04 Correlation: Is It A Coincidence?
Rubric:5 auto-grade questions (15 points), 1 teacher graded essay (15 points)
Students will receive one of the following essay questions:
- Describe a positive correlation scenario from your own life.
- Describe a negative correlation scenario from your own life.
Sample:
- A positive correlation in my life would be that the more time I spend with my baby cousin, the more he loves to be with me.
- A negative correlation in my life would be that the more time I spend asking my mom to stay out past curfew, the lesser my chances of staying out (as she gets annoyed with me).