Chapter 1 - research stuff Flashcards
What does ‘population’ refer to?
refers to entire group of research interest, a sample is drawn from the population.
What is a sample?
Subset or part of population that is selected for research purposes. Always smaller than population.
What is the purpose of sample and population
Sample is selected from the population; Sample can generalise for population.
What is random sampling?
sampling technique where each member of population has equal chance of being selected.
What are the limitations of random sampling?
Only truly be carried out if complete list of target population is available, this may be difficult to access and time-consuming.
What is stratified sampling?
Selecting sample from population comprised of subgroups, so that each subgroup is represented.
What are the advantages of random sampling?
Helps ensure highly representative sample enables generalisations with greater confidence.
What are the advantages of stratified sampling?
Enables researcher to sample specific groups within population for comparison purposes. Can provide greater precision for research findings.
What are the limitations of stratified sampling?
Only carried out if lists of target population are available and accessible. Representative sample cannot be obtained unless stratified random sampling occurs.
Very time-consuming and complex, expensive.
What is convenience sampling?
Selecging sample of individuals who are readily available.
What are the strengths of convenience sampling?
Typically quick, easy and inexpensive.
What are the limitations of convenience sampling?
Governed by chance, not systematic, orderly. Often produces biased sample, as favors particular individuals or groups.
What is a controlled experiment?
An experimental investigation of relationship between one or more IV’s a DV, controlling all other variables.
What is an experimental group in a controlled experiment?
The group that is exposed to the IV.
What is a control group in a controlled experiment?
The group that is not exposed to the IV.
What is ‘random allocation’ in a controlled experiment?
A procedure used to place participants in groups, so they have an equal chance of being in each group.
What is the ‘between subjects’ experimental design?
An experimental design where each participant is assigned to only one group.
e.g control group and experimental group.
What are the advantages of the ‘between subjects’ experimental design?
Not a need to spread out time period between experimental conditions. Experiment can be completed on one occasion, stops people from dropping out.
What are the limitations of the ‘between subjects’ experimental design?
Often a need for larger number of participants. Less control over participant variables, especially with small sample.
What is the ‘within subjects’ experimental design?
Each participant is in both experimental group and control group.
What are the advantages of the ‘within subjects’ experimental design?
- effectively control unwanted influence of variables arising from individual participant differences.
- tends to require smaller number of participants.
What are the limitations of the ‘within subjects’ experimental design?
- does not control all participant variables that can influence results.
- greater attrition (loss) rates, especially when conducted over multiple days.
What is a ‘mixed design’ experimental design?
An investigation that combines features of between subjects and within subjects designs.
- researcher can access potential differences between two or more separate groups of participants.
What are the strengths of a ‘mixed design’ experimental design?
Researches can capitalise on strengths of between subjects and within subjects designs.
What is a random error?
an error due to some chance factor or chance variation in a measurement
Errors occuring randomly
How do random errors affect studies?
They affect the precision of a measurement, producing unusual outliers.
What is a systematic error?
a measurement error produced by some factor that consistently favours one condition rather than the other.
Same error every time
What is an error?
Refers to difference between observed or calculated value and the true or perceived value.
What is uncertainty?
Reflects the lack of exact knowledge of the value of the quantity being measured.
True value - the value of something if it could be measured pefectly. E.g stress or feelings.
What does true value refer to?
The value of something if it could be measured pefectly. E.g stress or feelings.
What is precision?
Refers to how closely a set of measurements agree with each other.
What does precision NOT do?
Give indication of how close measurements are to the true value, not linked to accuracy.
What is accuracy?
How close it is to ‘true’ value of quantity being measured.
What is an extraneous variable?
Can/may have an effect on the DV
What is a confounding variable?
Has an effect on the DV, CANNOT be separated from the DV.
Unable to tell if IV OR confounding variable effected DV
Cross sectional?
Experiment/study at a specific point of time.
What is a longitudinal experiment?
Follow participants over an extended period of time.
How do systematic errors effect results of an experiment?
Present in all measurements, except for measurements involving counting.
