research methods (yr13) Flashcards
what is a longitudinal study?
research that is conducted over a long period of time in order to study long term effects
what is an example of a longitudinal study in psychology?
what are the characterises of the study and the pps?
Kohlberg - aimed to investigate the development of moral reasoning in children in order to create a series of stages that could apply to all. he used the same group of boys and assessed their responses to moral scenarios over a period of 12 years. the pps were aged 10-16 at the start and aged 22-28 by the end
explain the strengths of longitudinal studies (2)
- uses a repeated measures design so participant variables are controlled and all the other variables are kept constant
- effective in determining variable patterns over time. researchers can learn more about cause and effect relationships
explain the weaknesses of longitudinal studies (3)
- sample attrition as the study is conducted over a long period of time. it’s likely that those who drop out share similar characteristics and therefore the results become biased from a sample that’s too small
- risk of demand characteristics with a repeated measures design. pps are more likely to guess the aims of the study and change their behaviour accordingly
- hugely time consuming due to the fact that they extend over several years, which also makes them very expensive
explain the strengths of cross sectional studies (3)
- relatively quick compared to LS. they can be completed in less than a year but LS take several years
- recruitment for pps is easier due to the involvement being relatively short term
- fewer ethical considerations compared to LS
explain the weaknesses of cross sectional studies (2)
- participant variables may differ as a independent measure design so the groups of pps are different
- cohort effects - people who are of the same age share certain experiences which may bias the data and mean that valid comparisons cannot be made across groups
what term is important to look out for when answering questions about certain studies?
‘for this research’
what is involved in a PET scan?
involves administering radioactive glucose into the patient and the most active areas of the brain will require energy and use the glucose. radiation detectors are used to see the most active areas of the brain
what are the strengths of PET scans?
- painless and time efficient procedure
- detect cancer, see the spread and efficiency of the treatment
- high sensitivity - detect abnormalities missed by other scans
what are the weaknesses of PET scans?
- invasive as it requires the injection of a radioactive tracer
- exposure to radiation can cause health issues
- expensive
what is involved in an MRI?
uses a magnetic field that causes the atoms of the brain to change their alignment when the magnet is on and emit various radio signals when the magnet is turned off
what are the strengths of MRIs?
- gives extremely clear and details images of soft tissue structures that other imaging techniques cannot achieve
- doesn’t involve radiation so no harmful side effects - safer
what are the weaknesses of MRIs?
- really expensive and takes a while to complete the process
- cannot be used on patients or have metal in their body
- small confined space with loud noises - cause anxiety
what is involved in an EEG?
electrodes are placed on the scalp and electrical activity in different regions of the brain can be recorded
what are the strengths of EEGs?
- the test if painless and relatively cheap compared to other methods
- doesn’t involve exposure to strong magnetic fields or radiation in the same way as other techniques
- the equipment is more portable which allows for more convenient analysis of patients
what are the weaknesses of EEGs?
- could induce a seizure in those suffering from epilepsy or other disorders involving seizures
- hard to figure out where in the brain the electrical activity is coming from
what is involved in a CAT scan?
taking a series of x rays and combining them to form 2D/3D pictures of the area being scanned. sometimes a dye is injected as a contrast material
what are the strengths of CAT scans?
- high quality imaging
- fast so useful in emergencies such as detecting strokes
- detailed imaging so more accurate diagnosis
what are the weaknesses of CAT scans?
- only provides structure of the brain not electrical activity
- radiation exposure so cannot be used repeatedly
- patients may be allergic to contrast material preventing detailed images being created
what are the 5 methods of assessing validity?
face validity
content validity
concurrent validity
construct validity
predictive validity
what does face validity involve?
assessing whether a measuring instrument looks correct in the eyes of non-experts. takes places in early phases
what does content validity involve?
independent experts assess the validity of the measuring instrument but procedures are more rigourous
what does concurrent validity involve?
obtain 2 sets of scores; 1 from new procedure with unknown validity and 1 from other procedure with established validity. scores are measured and correlated against each other. high positive correlation = new procedure is valid
what does construct validity involve?
assess the extent that a test measures the target construct
what does predictive validity involve?
whether a test will predict future performance, indicated by its results
what are the 5 statistical tests?
chi square
sign test
spearman’s rho
mann whitney
wilcoxon
what are the 3 D’s used to select the correct statistical test?
data
design
difference
apply the 3 D’s to the chi square test
nominal data
independent groups
test of assocation
apply the 3 D’s to the sign test
nominal data
matched pairs
test of difference
apply the 3 D’s to the spearman’s rho test
at least ordinal data
repeated measures
test of correlation
apply the 3 D’s to the mann whitney test
at least ordinal data
test of difference
independent groups
apply the 3 D’s to the wilcoxon test
at least ordinal data
test of difference
matched pairs or repeated measures
what is the R rule in terms of statistical tests
if the name of the test has an R in it then you accept the experimental hypothesis if the observed value is equal to or more than the critical value
what is inter rater reliability?
measuring the extent to which researchers, scoring the same pps, achieve consistency of measurement with each other
what is the split half method?
splitting the test or questionnaire into 2 parts after data has been obtained from the pps e.g comparing results obtained from odd and even numbered questions
what is the test retest method?
presenting the pps with the same test on different occasions with no feedback given after the first presentation
