Correlation and Experiments
The correlation measures how closely two things vary together or how well one thing predicts another. It is used to DESCRIBE behaviour or events, but it cannot explain them.
The POSITIVE correlation. This means that two things either increase or decrease together. o Ex. The more violent TV you watch the more aggressive you are o Ex. if you have high grades in school you will have high grades in college o Ex. if you have low grades in high school you will have low grades in college as well. The NEGATIVE correlation. This means that as one thing increases the other thing decreases or vice versa. o Ex. People who score low on self-esteem generally score high on depression o Ex. The more people go over their optimal weight, the shorter they are expected to live.
This is a correlation or a relationship between two things that does not actually exist. If you believe that two things are related you often think that you see a relationship between them where there really isn’t one. These occur when we fail to see the entire picture. Ex. Superstitious beliefs like bad things happen when there’s a full moon. You will be likely to remember bad things on days that there is a full moon because you expect them to happen – because you already believe there is relationship between a full moon and bad things happening.
o We like to look for order, patters and sequences in our lives. We usually are able to find this order because many random events – events that occur purely by chance – do not always appear to be random.
The Directionality Problem: o When researchers study how poor readers read, they find that their eye movement patterns are erratic. o So based on this research, many educators assumed that “poor motor skills in the eye” CAUSED reading problems. o Their SOLUTION: “Eye movement training programs” to help children read better. o The REAL CAUSE = the opposite! o Slow reading and poor comprehension CAUSES erratic and odd eye movements.
The Third Variable Possibility: o A study on the disease, “Pellagra” which causes dizziness, fatigue, diarrhea and vomiting, found that people who had the disease also had poor plumbing and sewage where they lived. o Researchers CONCLUSION = Pellagra is caused by poor sanitary conditions. o But, Surgeon General Joseph Goldberger felt that the illness was caused by a poor diet, because the people who had the disease were poor and couldn’t afford an adequate diet.
How was this controversy resolved? o The Experimental Method The Control Group ate a balanced diet The experimental group ate a poor diet and ended up developing Pellagra. *** Correlation DOES NOT mean CAUSATION (a relationship between 2 things does not meant that one thing causes the other)
In order to explain behaviour, Psychologists must conduct CONTROLLED EXPERIMENTS. The idea behind an experiment is: o For one group of people, manipulate ONE factor, called the EXPERIMENTAL FACTOR or the INDEPENDENT VARIABLE. You are interested in studying the effect of this one factor. o For another group called the CONTROL GROUP, keep all the other factors CONSTANT or the same.
An experiment is always made up of TWO GROUPS o AN EXPERIMENTAL GROUP who receives the TREATMENT of the EXPERIMENTAL FACTOR. o A CONTROL GROUP who doesn’t receive the TREATMENT. *** Other than the treatment or the experimental factor that the experimental group receives, everything else between the two groups is the same.
When you randomly put people in groups, then the groups should be similar. This means that by randomly putting people in groups, they equal each other out on things like their age, their values, their opinions and any other characteristic. The idea behind random group assignment is that a person could just have easily have been in the experimental groups as in the control group. By random assigning, the groups become equal on everything EXCEPT the thing that we are testing (THE EXPERIMENTAL FACTOR). To see whether or not our EXPERIMENTAL FACTOR or INDEPENDENT VARIABLE has had an effect we must measure a dependent variable.