psychological investigations

strengths

• gain qualitative and quantitative data
• quick and easy to gain alot of data
• can see peoples opinions

weaknesses

• demand characteristics
• socially desirable response
• low reponse rate
• participants might react different to how they say they would
• participants may interpretate the questions differently

improvements

• ask different style questions, like fixed choice or scale questions which are both easier to analyse
• give different instructions to the participants
• change the format or environment
• ethics could be improved by keeping the information confidential

interview

strengths - detailed information. focus on individuals. relaxed environment            weaknesses - difficult to analyse. time consuming. expensive. interviewer biases

questionnaires

strengths - quick. lots of data. quantitative data is easier to analyse. convenient weaknesses - socailly desirable response. interpretation of questions. low response rate

bar charts - is to record data in categories                                                                 histogram - is to record grouped data

• mean = add values/number of values
• median = middle value
• mode = most common value
• range = biggest value - smallest value

strengths

• high ecological validilty
• naturally occurring behaviour
• reduced demand characteristics
• ethical issues
• cannot be artifical

weaknesses

• lack of control
• observers may affect behaviour if detected
• difficult to replicate
• more than 1 observer may be needed
• interpretation of behaviour

improvements

• more categories would mean increased validity
• different categories would make it more reliable
• more participants would increase validity and reliability
• ethics could be improved by gaining consent from the participants

reliability

• inter - rater = 2 observers
• inter - rater reliability = checking criteria before doing the observation

alternative

there will be a difference...

ex.1 there will be a different in that students will recall more information on a monday morning than they will on a friday afternoon ex.2 there will be a difference in the amount of money spent the week before christmas compared to the week after christmas

null

there will be no difference...

ex.1 there will be no difference in the amount of information students can recall on a monday morning compared to a friday afternoon and any difference that is shown will be due to chance ex.2 there will be no difference in the amount of money spent in the week before christmas then the week after christmas.

one-tailed hypothesis

states the direction in which the results are expected to go                                    ex.men drive faster then women

two-tailed hypothesis

doesn't give a predicted direction                                                                        ex.there is a difference in the speed that mean and women drive

opportunistic - available at the time

advantages - quick and cheap

disadvantages - non-representative sample making it difficult to generalise. demand characteristics

random - everyone has an equal chance of being selected

advantages - there's no biases

disadvantages - non-representative sample which would make it difficult to generalise. demand characteristics

systematic - done by using a formula, every nth person

advantages - quick

disadvantages - non-representative difficult to generalise. demand characteristics

self selecting - participants volunteer

advantages - affordable. quick way of gaining a sample. participants will be more co-operative as they have volunteered

disadvantages - demand characteristics

stratified - participants are representative of the whole population

advantages - most representative of all the types of sampling, this makes it easier to generalise

disadvantages - expensive. time consuming. demand characteristics

independent measures                                                                                              different participants are used for each condition

strengths - participants only have to do 1 condition. reduces boredom effects. reduces practise effects.

weaknesses - individual differences/participant variables might effect the results, for example having all the participants that are good at the activity in the same group. more participants would be needed

repeated measures                                                                                                   the same participants are used in each condition

strengths - individual differences/participant variables wouldn't effect the results because the same people are being used for all of the conditions

weaknesses - participants might suffer from practise effects by naturally getting better the second time. participants might suffer from boredom effects

counterbalancing 

alternating the order that participants perform in different conditions - to eliminate order effects ex.group 1 does a and then b, while group 2 does b and then a

randomisation   

material for each condition is presented in a random order - to prevent order effects

observation types

• structured observation is the use of pre-determined categories of behaviour
• unstructured observation is where you record everything

time sampling                                                                                               observations may be made at regular time

event sampling                                                                                                     keeping a tally chart of each time a type of behaviour occurs

point sampling                                                                                                         focusing on 1 individual for a certain amount of time

lab experiement                                                                                                   artificial environment with tightly controlled variables

strengths - lots of control. easy to replicate. can use necessary equipment. cheap and isn't time consuming

weaknesses - demand characteristics. artificial environment. low ecological validity. experimenter biases

field experiement                                                                                                  natural environment with independent variable manipulated by the researcher

strengths - naturally occuring behaviour. high in ecological validity

weaknesses - time consuming and expensive

natural/quasi experiment                                                                                       natural changes in the independant variable are used and it's not manipulated

strengths - it may be ethically unexceptable to manipulate the independant variable. reduced demand characteristics. no experimenter bias

weaknesses - the indenpendant variable is not controlled. there is no control over allocation of participants to the groups.

                                                                                                                          ethical issues

confidentuality - if experimenters you the results the will have to keep it confidentual and not use the participants name

a correlation is a statistical technique used to quantify the strength or relationships between 2 variables

strengths - it can tell us whether there is a relationship between 2 variables and this can be used as an indicator of futher research

weaknesses - it doesn't tell us the cause and effect and we can't assume whis so it is misleading. the lack of correlation doesn't mean that there is no relationship

after the points are plotted on a scattergraph, you draw a line of best fit

if both variables increase together this means there is a positive correlation                      if one varibale increases as the other decreases there is a negitive correlation                 if no line of best fit can be drawn there is no correlation