Slides in this set
Different methods of investigation
· You need to know about several different research techniques,
when they are used, and the strengths and weaknesses of each.
Research method: Description:
Correlation Statistical technique - measures
strength of relationship between
Experiment An independent variable is manipulated
while others controlled, to see effects
on a dependent variable.
Interview Used to gain in-depth information and
Naturalistic observation Watching behaviour, as it occurs
spontaneously, in a natural setting.
Questionnaire survey A snapshot of large number of people's
attitudes, opinions or behaviour…read more
Aims and hypotheses
· The aim of an investigation is its general purpose. What are you trying to
achieve in the investigation?
· The hypothesis is a precise, testable statement or prediction about the
expected outcome of an investigation.
· A 'null hypothesis' prediction is one that states results are due to chance
and are not significant in terms of supporting the idea being investigated.
For example: There is no evidence that there is a difference between
groups in the amount they remember.
· A research hypothesis prediction is one that states that results are not
due to chance and that they are significant in terms of supporting the idea
being investigated. For example: There is evidence that there is a
difference between groups in the amount they remember.
· A one-tailed hypothesis is a directional hypothesis.
For example: Instead of saying there will be a difference between groups
in the amount they remember, you predict which group will remember
· A two-tailed hypothesis is one in which the direction of results is not
For example: You may predict a difference between groups, but have no
idea which way the difference will fall.…read more
Factors associated with good design
The following factors are important to consider when designing
· A pilot study is a test run on a few participants this enables you to
check for design faults before carrying out an investigation on a
larger scale, this is a routine procedure especially used when
carrying out questionnaires.
· Reliability of results is very important, so if a study is replicated
the findings should be similar.
· Validity, does a test measure what it was designed to measure.
For example, do IQ tests really measure 'intelligence'?
· Internal validity, extent to which study is free of design faults,
which may affect results.
· External Validity - `Ecological validity ' OR `Population validity'. This
means the extent to which generalisation can be made from the
test environment and the population to other situations.…read more
Choosing participants - sampling
· Random sampling: Everyone in the entire target
population has an equal chance of being selected.
· Opportunity sampling: Uses people from target
population available at the time.
· Systematic sampling: Chooses subjects in a
systematic way. For example, every 10th person from
a list or register.
· Self-selected sample: Participants volunteer. For
example, by answering an advert.
· Stratified sampling: Divides target population into
groups, people in sample from each group in same
proportions as population. So you would have a
higher number of people between the ages of 20-30
than 70-80.…read more
Relationships between researchers and
Ways in which either the researcher or the participants can influence the results
this is known as "causing bias".
· Researcher effects: Researcher can affect the behaviour of the participants, thus
affecting the results of the study. For example: The researcher might unwittingly
communicate his expectations to the participants. This could happen through only
small changes in body language or tone of voice. Or it can be in the interpretation
of data, a researcher may read into things more of what he or she would like to
find! An attractive researcher might affect participant responses. For example,
male researchers smile at female participants more than they do at male ones
· Even rats learned mazes faster when expected to! (Rosenthal, 1966) Just the
presence of the researcher can affect participant behaviour, more so if the
researcher is filming people.
· Demand characteristics: Participants might read things into the situation and start
changing their behaviour they respond to the perceived demands of the study.
Participants may worry about being in a psychological study and want to appear
'normal', this may change their behaviour. Participants may try to guess what the
investigation is about then behave in the way they think the investigator wants
them to. On the other hand, they may deliberately try to behave in an unexpected
way. Unofficially known as the "f*** you effect"). Participants might just try to
'look good' (social desirability) and behave out of character or not tell the truth.
This can be a problem for questionnaires on sensitive issues.…read more