Variables/ psychological investigations

Seite 1

working with variables! 1. Independent and dependent variables IV/ DV Independent variable: the factor that's being manipulated directly by the experimenter to observe the effects on the DV (only in laboratories)

dependent variable: what we are trying to measure, the factor that depends on the IV ( Independent variable)

example:

IV: Exercise v No exercise

DV: Sleep

the IV and DV are used to determine cause and effect relationship.

2. covariables: they are used when conducting a correlation because the IV and DV cant be determined i.e. no cause and effect

the two variables that are being correlated are called Covariables.

3. Operationalisation variables must be operationalised

this is when variables must be defined in a way that means they can be tested. it MUST be specific.

why is operationalisation is important?

so that the variables are not vague e.g. what do we mean by educational achievement? etc... being specific

so that the research is replicable- its needed to check for objectivity- validity/ reliability...

so the research is objective- avoids bias

research methods!!

There are three types of research methods: 1. lab experiments: IV is manipulated

very controlled environment

Advantages:

determines cause and effect

extraneous variables minimised

easily replicated due to high level of control of the variables

Disadvantages:

Creating artificial situations due to high level of control -------> may not generalise

Investigator effects

Demand characteristics: PP's are able to guess the aim of the study

2. field experiments:

IV is manipulated

occurs in more natural surroundings

Advantages:

establish cause and effect between IV and DV

higher ecological validity

less likely demand characteristics/ social desirability: fear of the judgement of others

Disadvantages:

less control on extraneous variables

harder to replicate as not controlled in a laboratory settings.

3. natural experiments:

IV occurs naturally

pp's not randomly allocated to groups

Advantages:

enables psychologists to study "real" problems

allows research where IV is not ethical/ practical to manipulate

Disadvantages:

cannot demonstrate cause and effect relationships

extraneous variables due to the lack of control

investigator effects- where the experiment unintentionally gives clues to the purpose of the experiment.

social desirability

4. correlations:

used to show relationship between two variables

looking at the strength and directions e.g. positive correlation/ negative correlation or zero correlation

advantages:

used when its unethical to manipulate the variables

disadvantages:

cannot be used to determine cause and effect

hidden extraneous variables that caused the relationship!

Observations!

A. naturalistic observations:

in this situation no variables are manipulated, as there is no control hence the word "naturalistic" its natural occurring

advantages:

useful to study behaviour when variables cannot be determined.

high ecological validity- due to the natural surroundings leading to more natural behaviour.

disadvantages:

replication is difficult

extraneous variables due to no control

observer bias----> low inter-observer reliability

social desirability if PP's know that they are being tested

B. controlled observation:

variables are manipulated by the observer e.g. the environment or the situation

e.g. Ainsworth strange situation

advantages:

easily change variables in order to see the effect they may have on behaviour

disadvantages:

low ecological validity

low inter-observer reliability

investigator effects

social desirability

what is investigator effects?

where the experimenter alters the behaviour of the participants.

its a way of saying experimenter bias: where the experimenter unintentionally gives clues to the PP's about the purpose of the experiment, therefore this can change the behaviour of them and can effect the validity of the observation.

C. contents analysis: basically analysing the content of an already done research!

indirect observation----> it is based on written and verbal materials such as books, diaries, interviews etc...

advantages:

high ecological validity because the evidence we gather from it based on what people have produced, have done

can be easily replicated!

disadvantages:

lead to observer bias when interpreting the evidence as different people interpret the evidence differently

Self report questionnaires: set of written questions usually close ques. to produce quantitative data

pros:

easily repeated

lots of data can be gathered quickly due to ease of replication

no social desirability as anonymous questionnaires motivates people to be honest in their answers

cons:

leading questions

social desirability MAY occur

memory problems due to people not being accurate in their responses

sample bias---> not aimed at target audience

self report interviews:

questions usually are open to gain qualitative date- opinions and details info.

giving a chance for a follow up questions

usually unstructured

advantages:

detailed info. collected

rapport can be built between the interviewer and the PP - where trust is built between both therefore the pp response can be more valid

disadvantages:

face to face situations can create social desirability

could have leading questions/ interviewer bias

people may not be accurate in their responses due to memory

sample may be biased