1. Comparing quantitative and qualitative data Qualitative data Gains access to thoughts and feelings that may not be accessed using quantitative methods with closed questions. - More difficult to detect patterns and draw conclusions because of the large amount of data usually collected.

2. Comparing quantitative and qualitative data Quantitative data Easier to analyse because the data are given in numbers that can be summarised using measures of central tendency and dispersion as well as graphs. - Oversimplifies reality and human experience.

3. Meta-analysis A researcher combines the results of several studies that have addressed similar aims/hypotheses to reach a conclusion. Analysing the results from a group of studies rather than from just one study can allow more reliable conclusions to be drawn. - The research designs in the different studies may vary which means that the studies are not truly comparable and therefore the conclusions made are not always valid.

4. Cross-cultural study Researchers compare behaviours in different cultures. Enables psychologists to see whether some behaviours are universal (e.g. attachment). - The group of PTs may not be representative of the culture and yet the researchers may make generalisations about the whole culture.

5. Longitudinal study When a study is conducted over a long period of time in order to observe long-term effects in the same individual. Can make comparisons between the same individual at different ages (increasing reliability). - Attrition – the loss of PTs from a study over time which is likely to leave a biased sample or a sample which is too small.