SCIENTIFIC RESEARCH METHODOLOGIES

Within subjects design

participants complete every experimental condition

One group of participants completing both conditions

Within subjects design

strengths of within subjects design

- Results more likely due to IV

- Less people required

- Good for real world settings

Limitations of within subjects design

- Order effects

- Participant withdrawal can impact results

Between subjects design

Individuals are divided into different groups and complete only one experimental condition

Strengths of between subjects

- Less time consuming

- No order effects

Limitations of between subjects

- Requires more participants

- Participant differences across groups

Mixed design

Combines elements of within and between subjects designs

strengths of mixed design

- Comparison across conditions over time

- Allows multiple experimental conditions to be compared to the control group

limitations of the mixed design

- Costly and time consuming

- Demand for researchers to be across multiple methods

Example of mixed design

- Measure participants anxiety levels BEFORE public speaking

- Measure AFTER public speaking

- Compare over time

Validity

The extent to which psychological tools and investigations truly support their findings or conclusions

Internal validity

The extend to which an investigation truly measures or investigates what it claims to

Example of low internal validity

A psychology SAC that contains legal studies content

External validity

The extent to which the results of an investigation can be applied to similar individuals in different settings

Example of low external validity

Using flashcards to memorise psychology may not be effective in maths

Reproducibility

the extent to which successive measurements or studies produce the same results when repeated under different conditions

Example high reproducibility

Boiling of water at any time of day by any observer or experimental conditions

Factors impacting reproducibility

Different participants, time, observer, and/or environmental conditions

Example of low reproducibility

Assessing long term ecological impacts on a specific pesticide will produce different results depending on plan, location, weather etc..

Repeatability

The extent to which the same study or measure used under the same conditions will produce the same results

Example of high repeatability

Measure of acceleration due to gravity

Example of low repeatability

The impact of an astronomical event like the observation of a particular comet