Research Methods
Lesson 2
Introduction to Variables Investigation & Design Produced by
Introduction on variables: • In psychology anything that can vary or change is regarded to be a variable. Variables change from group to group, person to person and even within a person. • Some examples of variables are age, intelligence, personality, attachment, attraction, memory or recall ability, height, weight and response times. • Variables do not have to be quantitative by value. They can be qualitative. For example the variable gender has two attributes male and female which are qualitative.
Defining variables in research: • Variables in any psychological research need to be defined. For example, if an investigator says he / she is carrying out an investigation on bullying. They need to explain or define bullying in terms of their research. • For example, there are many types of bullying or factors that contribute to bullying. In the case of the above investigator he / she may be investigating bullying in the form of text messaging. So their definition of bullying in their research implies text messaging only. • Note that text messaging is not the only factor that constitutes bullying, factors such as kicking, play fighting, pushing, spitting, verbal statements and many other factors have been deliberately excluded for the purpose of this research.
Operationalising Variables: • Many of the variables psychologists investigate are abstract concepts. By abstract we mean things that are not visible at times or physical by nature. For example, the mind and personality or intelligence. • Operationalisation refers to process of making variables physically testable or measurable. • In psychology this is done by recording or measuring some aspects of observable behaviour that is indicative of the variable under investigation. •
See examples on the next slide.
Examples of operationalising a variable: 1) •
Investigator intends investigating aggression: Aggression is an abstract variable and it can be operationalised by measuring observable behaviour such as the amount of kicks or punches a person has thrown to an object or another person.
2) •
Investigator intends investigating intelligence: Intelligence is an abstract variable and it can be operationalised by measuring the number of puzzles a person can solve within an hour or by taking an intelligence test.
The independent variable (IV): • Psychological research focuses on the relationship between two variables. • The reason for this is to establish cause and effect relationship. Psychologists want to investigate and see what causes something and what the effects are. • Cause and effect relationships can only be established by using an experimental method. Here the investigator will manipulate only one variable to observe its effect whilst making sure all other variables are held constant. • The variable that is manipulated is the independent variable or (IV).
• By keeping all other variables constant we mean making sure that the experiment is controlled. • This entails making sure that the participants in the two groups taking part in an experiment are as similar as possible. Have the same conditions during the course of the experiment. • Receive the same identical instructions, have the same amount of time to carry out a task. That participants are tested or given a task at the same time. The rooms or labs where the participants are participating are identical by nature. The times of a given task are identical. The room temperatures are identical.
• The reason for having controls or keeping all other variables constant is that when we analyse the data at the end of an experiment from the groups participating. If any differences are found between the two groups, we can then say that these differences observed were caused by the manipulation of the (IV) independent variable only. • If however, our controls are not good enough then the differences found could be due to variables other than the (IV) independent variable that are changing or varying and causing the differences found between the two groups in an experiment. • Variables such as these that change during an investigation are referred to as extraneous or confounding variables and can be identified after an experiment has taken place.
• Let’s say hypothetically we want to investigate the effect of alcohol on response times. We want to establish whether alcohol (the cause) causes poor response times (the effect). • As you should have identified this is a cause and effect relationship that we want to investigate, we will use an experimental method. • We could have two identical groups participating. One group will have some alcohol and the other group will have none. After a period of time when we have established that the alcohol has taken some effect. We could get the two groups to carry out an identical task. • The results should prove that those under the influence of alcohol showed slower response times.
• If that is the case then we can say that alcohol (the cause) does cause a delay in response times (the effect). • However, say hypothetically the results turn out to be that the group that had no alcohol showed slower response times. Because we know from theory that this cannot be true, we can say that there was a variable or even variables other than the (IV) independent variable that were changing between the two groups when they should have been controlled for or kept constant. • These variables that are changing without our knowledge or because of our poor design are referred to as confounding or extraneous variables. Once identified and controlled for the experiment is usually replicated with a new sample of participants hoping to see the desired effects based on our background literature and research.
• Example 1: Participants who can be identified as having a secure attachment during childhood with their caregivers are less likely to end up in broken relationships with their partners in later life. The IV that is going to be manipulated
IV is manipulated by having one group with secure attachments and the other with insecure attachments.
• Example 2: There will be a significant difference in the number of words recalled between participants who learn from word list with categories and those that learn from word list without categories. The IV that is going to be manipulated
IV is manipulated by having one group using words with categories and the other without categories.
Dependent variable: • The dependent variable can be defined as the outcome or the effect of the manipulation of the independent variable in the two groups participating in the experiment whilst all other variables are kept constant or controlled for. • Any difference found between the two groups in an investigation can be explained as the effect or outcome due to the manipulation of the (IV). This effect or outcome is the dependent variable (DV) • It is totally dependent on the manipulation of the (IV). • Let’s have a look at our two previous examples on the next slide.
• The dependent variable (DV) would be the effect secure and insecure relationships during childhood has on relationship with partners in later life. The IV that is going to be manipulated
IV is manipulated by having one group with secure attachments and the other with insecure attachments.
The DV dependent variable
• The DV dependent variable would be the effect word list with categories or no categories has on memory or recall of words. The IV that is going to be manipulated.
IV is manipulated by having one group using words with categories and the other without categories.
The DV dependent variable
Further Reading: • www.psychologyrevise.com Investigation and Design •
Research Methods Variables.
Wider reading – more practical examples on variables.