RESEARCH METHODS Flashcards
Random sampling
involves selecting participants from the population in such a way that each member of the population has an equal chance of being selected to participate in the study
S & W RANDOM SAMPLING
Strength
A large enough random sample is likely to be representative of the population, improving external validity
Limitations
- Small random samples may not be representative of the population, reducing the external validity.
- It may be difficult, time consuming, impossible or unethical to obtain names of all members of the population.
Stratified sampling technique
The population is first divided into subgroups, and participants are randomly selected from each subgroup, in the proportion that they appear in the population
Stratified sampling technique S&W
Strengths
- A large enough stratified sample is likely to be representative of the population, improving external validity.
- Important subgroups of a population are ensured fair representation.
Limitations
- It may be difficult, impossible or unethical to obtain names of all members of the population.
- It is more time consuming than using a random sampling technique because of the need to form subgroups and any pre-testing required.
A controlled experiment
Participants are randomly allocated to an experimental group or a control group, and the results of the groups are then compared
aim is to find out whether an IV has an effect on a DV
**
S&W for A controlled experiment
Strengths
- Controlled experiments can identify a cause-and-effect relationship between an IV and a DV.
- Results may be generalised to the population of interest if the study is deemed to have good validity.
Limitations
- Controlled experiments require strictly controlled conditions, which may be difficult to maintain, so results may be influenced by extraneous variables.
- Participant behaviour may be influenced by the artificial nature of the setting.
aim is to find out whether an IV has an effect on a DV
Random allocation
Involves dividing the sample into groups in such a way that each participant has an equal chance of being placed into the experimental group or the control group
Ensures the groups of a study are equal in participant characteristics
, and therefore any change to the results of a study is more likely to be due to the effect of the independent variabl
Simple controlled experiment
the participants are allocated to one experimental group and one control group
There are three investigation designs that involve different ways that participants experience the experimental and control conditions
between subejct design, within subject design, mixed design
A between subjects design
When participants are randomly allocated to either the control or the experimental condition
S&W of between subjects design
Strengths
- most time-efficient design because both groups can be tested at the same time and no pre-testing is required.
- It has a lower rate of participant withdrawal than a within subjects design because participants only complete one condition.
**Limitiations **
- More participants are needed in a between subjects design than a within subjects design.
- There is less control over the extraneous variable of participant variables between groups, which may influence results in an unwanted way, lowering validity.
within subject design
involves all participants in the sample completing both the experimental and control conditions
within subject design
involves all participants in the sample completing both the experimental and control conditions
S&W of within subject design
Strengths
- In a within subjects design, there is no extraneous variable of participant variables between groups, improving validity.
- Fewer participants are needed than in a between subjects design.
Limitations
- There is less control over participant knowledge of the study. The extraneous variable of prior participation in the first condition may influence their behaviour while completing the second condition.
- It is more time consuming than a between subjects design because both conditions cannot be tested at the same time.
Mixed design
A simple mixed design investigation may test the effect of one independent variable at two time periods, such as through a pre-test and a post-test.
combination of a between subjects design and a within subjects design
