Another commonly used and frequently misinterpreted form of study is the correlational study. Correlations refer to relationships between two things - two factors or variables. Such conclusions can't be made, although often such conclusions are made. Recently a study addressed the issue of changes in neurotransmitter levels and behavior. There has recently been some suggestion that if we were to alter serotonin levels this would fix all the world's ills.
Correlational studies suggest low serotonin is bad - a very simplistic statement.
Read this short article to get an understanding of the fact that behavior affects the body and the body affects behavior - beware of making cause and effect conclusions when looking at correlational data. Another example - one study concluded that bras cause cancer. Hmm, this isn't at all amusing, but hopefully I've got you somewhat interested. I love psychology and really think that I am most fortunate to have the opportunity to share my enthusiasm with you. All behavior is produced by the nervous system, so we have to have a working knowledge of the nervous system.