Research Methods Flashcards
(111 cards)
Types of hypothesis
- null
- alternative
Null hypothesis
- IV will not affect the DV
- no relationship between observed variables
Alternative hypothesis
IV will affect DV
Types of variable
- independent
- dependent
- extraneous
Independent variable
What the researcher changes/manipulates to test its effect on the DV
Dependent variable
The outcome/effect that is being measured in a study
Extraneous variable
Unwanted variable that can affect the DV
Target population
Group of people that researcher wants to generalise findings to
Sample
Small portion of Ps from target population being studied
Types of Sampling
- random
- opportunity
- systematic
- stratified
Random sampling
- selection of participants is random
- e.g- names out of a hat or numbered and selected by computer
Random sampling STRENGTH
- unbiased results
- all target population have equal chance of being picked
- sample is more representative of target population, more validity
Random sampling WEAKNESS
- takes much time and effort
- have to obtain list of all members of target population and number them, then may not want to take part
- effort may not be with it
Opportunity sampling
Asking those who are most easily available
Opportunity sampling STRENGTH
- quick and easy
- choose people who are nearby and available
- less time consuming
Opportunity sampling WEAKNESS
- greater chance of being biased
- sample drawn from narrow part of target population, may only have 1 certain type of person - may be participant variables
- reduces generalisability/reliability of results
Systematic sampling
Selecting every ‘nth’ member of the target population as a participant
Systematic sampling STRENGTH
- avoids researcher bias
- researcher has no say over who’s - selected
- more representative
Systematic sampling WEAKNESS
- need bigger sample size
- e.g- if you require 100 Ps for study and picked every 10 Ps, 1000 Ps would be needed
- may be time consuming method
Stratified sampling
- sub-groups within target population identified
- Ps chosen from each sub-group in proportion to their occurrence in target population
Stratified sampling STRENGTH
- most representative sampling method
- all subgroups represented in proportion to target population
- findings should have high reliability/validity to make generalisations to target population
Stratified sampling WEAKNESS
- time consuming method
- have to identify sub-groups, select necessary Ps and attempt to get them proportionate
- difficult/impractical method to use
Experimental designs
- independent groups
- repeated measures
- matched pairs
Independent groups
- Ps divided into (usually 2) subgroups
- groups take part in different experimental condition
- used for comparison