Psychology & Statistics

Psychology & Statistics

The purpose of this essay is briefly explain the importance of understanding statistics in the psychological field. Psychologists rely on experiments and other research to gather evidence and construct theories. Generally, after formulating a hypothesis a researcher (or a group of researchers) will design an experiment to test the prediction or educated guess. Likewise, a review of the literature published on the subject is usually undertaken to get a broader picture. Also, articles which do not cover any primary research but review existent research on a subject, are called ‘review articles’ and a meta-analysis may or may not have been carried on the findings reviewed. The type of measures used also depends on the field one is most interested in psychology; to illustrate, neuroscientists may prefer to turn to fMRI (functional Magnetic Resonance Imagery) studies and neuron staining, while psychopathologists might first look at lesion studies and clinical cases.

An integral part of psychological theories comes from questioning, such as surveys and questionnaires. Indeed, most psychology (and business) students had to design at least one questionnaire during their undergraduate or college years. Questionnaire and interview questions may be open-ended or closed-ended. The two different types of questions correspond to qualitative and quantitative answers, respectively. An example of an open-ended question would be: How did you spend last summer? Conversely, closed-ended questions may be forced choice (such as answering yes or no, or fill in the blank), and multiple choice. Multiple choice questions are usually coded on the 5-point Likert-type scale and the results are then analysed using statistical methods.

Office Furniture. Illustration: Megan Jorgensen (Elena)

Psychologists also use other types of research methods, such as naturalistic observation, which involves observing an activity without intervening in any way. Precisely, the Hawthorne effect refers to the fact that people may behave differently when aware of being observed (or participating in an experiment). Likewise, psychologists often draw conclusions from correlations, but without implying causality. Thus, a correlation simply means that two variables move together, a positive correlation means that as X increases/decreases, Y also increases/decreases; while a negative correlation shows that the two variables move in opposite directions (as X increases/decreases, Y decreases/increases). Further, to meet the validity criterion, experimental results must be reliable and replicable.

Furthermore, longitudinal studies are carried over long periods of time, sometimes across generations. Alternatively, genetic studies may focus on fraternal or identical (monozygotic) twins. For example, studies on identical twins have shown that schizophrenia onset appears to follow a stress-diathesis model, in which having the genes is sufficient to develop the mental illness solely in the presence of environmental stressors (as evidenced by cases when in an identical twin pair, both of whom share the same genetic make-up, but only one of whom develops schizophrenia). Although the concordance and likelihood remain very high the closer the relative.

Perhaps one of the most fantastic anecdotes about genetic twin studies is the study of two identical twins who were separated at birth and adopted into two different families, in different Commonwealth countries. However, when the two brothers reunited in their forties, they noticed that not only had they chosen the same profession, led the same lifestyle and even married, divorced and remarried women with the same names, they even wore the same clothes. Such an argument lends credence to the nature side of the nature-nurture heated debate. Nowadays, most psychologists would agree that an interplay, or interaction, of both genes and environment, shapes individuals’ physical and mental health, personalities and other traits. Thus, the purpose of the present paper was to highlight the fundamental role that statistics and statistical analysis play in understanding psychology.