AQA A-level Psychology research methods Set 6

what are strengths of stratified sampling

likely that this method produces a representative sample since its designed to accurately represent composition of population

what are the weakness’s of stratified sampling

unlikely that this sample is completely representative as all people are different, requires detailed knowledge of the population characteristics

what is systematic allocation

the composition of the population represents the proportions of people in certain subgroups (strata)

how do you carry out systematic allocation

every nth member of the target population is selected e.g. every 5th student on the register

what are the strengths of systematic allocation

avoids researcher bias as once the sampling systems are established the researcher has no influence

what are the weakness’s of systematic allocation

more lengthy procedure than opportunity sampling, still may have bias e.g. Every 4th person is male

what is a correlation

a descriptive statistical technique that measures the relationship between variables

what are the statistics involved in correlations

numerical value between -1 and +1 to describe the degree of the relationship between 2 variables (correlation coefficient)

what does it mean if a value is closer to 1

the more those 2 variables tend to vary together i.e. stronger relationship

what is a positive correlation

the higher the value of one variables, the higher the value of the other variable e.g. go in same direction

what is a negative correlation

the variables tend to go in opposite directions e.g. the lower the value of one value, the higher the other

what does a negative correlation mean

that there is no correlation

how would you identify a strong correlation

an area of points clustering around an imaginary line and ascending

how would you identify a strong negative correlation

an area of points plotted along a descending line

how would you identify little or no correlation

a coefficient near 0 and points would be randomly placed

why is the gradient not an indicator of the type of correlation

correlations can ONLY be determined by how closely plotted points are

what do you need to do when writing a correlational hypothesis

always operationalise the variables and use terms positive and negative if it is a directional hypothesis

why CANT you use an experimental hypothesis in a correlation

it is NOT an experiment

what are correlational hypothesis used for

investigating the extent of a relationship between variables that are likely to co-vary

how are experiments and correlations different

experiments involved the deliberate change of one variable whereas correlations don’t include manipulation of variables