Quasi experiments

• Quasi experiments are types of natural experiments where the researcher has no control over the IV. The IV is based on existing differences between participants (e.g. a participant with depression and a participant without depression)
• A strength of quasi experiments is that they allow researchers to investigate variables that would be unethical to manipulate directly. For example, trying to induce depression in a participant would be highly unethical as it could cause considerable harm to participants. By using existing cases of depression (or other traits), we are able to investigate the effect of very important behaviour without having to cause significant harm
• A weakness of quasi experiments is that the cause and effect relationship between the IV and DV is weakened because participants from different groups, e.g. depression and no depression, will have individual differences beyond the trait difference being measured by the researchers. e.g. participants in the depression and no depression groups may differ in terms of their background, socio-economic status, IQ, age, which would act as EVs