Different methods of investigation include:
Correlation Statistical technique - measures strength of relationship between variables.
Experiment An independent variable is manipulated while others controlled, to see effects on a dependent variable.
Interview Used to gain in-depth information and individual views.
Naturalistic observation Watching behaviour, as it occurs spontaneously, in a natural setting.
Questionnaire survey A snapshot of large number of people's attitudes, opinions or behaviour.
Correlation is a statistical technique used to quantify the strength of relationship between two variables.
Used a lot in psychology investigations, for example Murstein (1972) carried out a correlation analysis of ratings of attractiveness in partners ('computer dance' study).
Strengths and weaknesses of correlation
Strengths: Weaknesses Calculating the strength of a relationship between variables. Cannot assume cause and effect, strong correlation between variables may be misleading. Useful as a pointer for further, more detailed research. Lack of correlation may not mean there is no relationship, it could be non-linear.
Independent variable (IV): Variable the experimenter manipulates - assumed to have a direct effect on the dependent variable.
Dependent variable (DV): Variable the experimenter measures, after making changes to the IV which are assumed to affect the DV.
Extraneous variables (Ex Vs): Other variables, apart from the IV, that might affect the DV. They might be important enough to provide alternative explanations for the effects, for example, confounding variables.
Laboratory experiment: Artificial environment with tight controls over variables.
Field experiment: Natural environment with independent variable manipulated by researchers.
Natural experiment: Natural changes in independent variable are used - it is not manipulated.
Interviews are face-to-face conversations, these can be unstructured, apparently informal chats, or they can be formal, structured interviews with pre-determined questions. For example, clinical tests used in psychiatry.
Interviews are recorded for later, in-depth analysis.
Strengths: Weaknesses: Detailed information can be obtained and avoids oversimplifying complex issues. Difficult to analyse if unstructured and qualitative in nature. Greater attention to individual's point of view this is important in clinical psychology. Time-consuming, expensive. Unstructured, casual interviews may encourage openness in answers. Possible interviewer effects. For example, people affected by attractiveness of interviewer!
Watching the behaviour of humans or animals in a natural environment.
The researcher does not manipulate variables and does not interfere with things - they try to remain inconspicuous.
Strengths: Weaknesses: More natural behaviour occurs if people are unaware of observation. Observer may affect behaviour if detected. Studying of animals that cannot be observed in captivity. Difficult to replicate - cannot control extraneous variables. Study of situations that cannot be artificially set up. Need for more than one observer.
When designing a questionnaire, there are several ways you can approach the study:
Use closed questions (fixed choice of answers), to generate data for easy analysis.
Use open questions (space to write any answer) for more detailed individual answers.
Keep questions and instructions clear and easy to understand.
Ask purposeful questions to help find information needed for the study.
Pre-code closed questions for quick analysis of the answers.
Carry out a pilot study first, a test run, making changes if needed.
Use attitude scales to test strength of feeling.