Chapter One
Review questions: suggested answers
1 a A sample is a group that is a subset or part of a larger group (the population) chosen to be
studied for research purposes, whereas a population is the larger group from which the
sample is taken.
b It is important since the researcher cannot look at every existing record; therefore, they
select a sample that accurately reflects the population of interest so that, after the research,
the data from the sample can be generalised to the population under study. Researchers
draw a sample from a population of interest; for example, all VCE students. Therefore, the
sample should be representative of the population.
2 a Random sampling is the procedure that ensures that every member of the population
under study has an equal chance of being selected in the sample for the research.
Stratified sampling involves dividing the population into subgroups (or strata) and then
selecting a separate sample from each stratum, in the same proportions as they occur in
the target population.
b Random and stratified samples are alike in that both are random and both are
representative of the population under study. However, they are different because in a
random sample no effort is made to ensure that subgroups within the population are
proportionally represented.
c To select participants to receive the recording device, one could take the electoral roll of
the town, number all residents and using a random number generator, say on computer,
select the number of participants required. If two or more participants from the same
residence were selected, further sampling could take place in the same way. Therefore,
everyone in the population would have an equal chance of being selected into the sample.
If subgroups within the viewing audience could be identified (for example, young children
not on electoral rolls), and are required to make the sample representative, census data
might be a better source for sampling.
3 Participant selection refers to the choice of subjects from the larger population, whereas
participant allocation refers to the placing of sample participants into their different groups in
the research study.
4 a Random allocation refers to the procedure of assigning participants to the various groups
within an experiment so that each participant has an equal chance of being assigned to
any group. It is used so that each group within the experiment has a balance of important
personal characteristics of participants.
b Random allocation refers to the equal likelihood of each participant in the sample to
be placed in any experimental group. Random sampling, however, refers to the equal
likelihood of each subject in the population to be selected for the sample.
5 a The experimental group in a study is exposed to the independent variable. The control group
is not exposed to the independent variable, but is treated identically in all other ways.
b The control group is used in order to provide a comparison with the experimental group
(to determine the effects of the independent variable).
© Macmillan Education Australia 2005. Unauthorised copying prohibited.
Psychology VCE Units 3 & 4
Research methods in psychology
© Macmillan Education Australia 2005. Unauthorised copying prohibited.
PAGE
23
Learning Activity 7
Review questions: suggested answers
1 The placebo effect occurs where participants in an experiment can alter their behaviour
simply because they believe that they have been subject to some form of experimental
‘treatment’, which should have an effect. For example, students who attend Psychology
summer school to improve their study may show improved scores simply because they know
that the course was meant to improve their results and not because the course was effective.
2 It is possible that an experimenter who knows the expected outcome of an experiment
may consciously or unconsciously affect the behaviour of participants in the experiment.
The experimenter effect occurs when the experimenter’s personal characteristics, actions or
treatment of the data affects the results.
3 Participant and experimenter expectations can affect the outcome of an experiment as, in
both situations, the results are influenced by what the people believe should happen, rather
than by the independent variable. The results may therefore be measuring the unintentional
influence of participants, or experimenter, rather than the influence of the independent
variable.
4 To overcome the placebo effect a single-blind procedure can be used. In a single-blind design,
the participants do not know whether they are in an experimental group or a control group.
To overcome the placebo and the experimenter effects a double-blind procedure can be used.
In such a design, both the participants and the researchers (dealing with the participants) do
not know to which group the participants have been allocated.
5 a In the Rosenthal and Jacobson (1968) experiment, it is important to note that the teachers
are the subjects, their ‘knowledge’ of their students’ ability is the IV, and the students’
performance is the DV. A single-blind design would have meant that the teachers did not
know whether their students were ‘fast’ or ‘slow’ learners, and this would have prevented
their influence on student performance.
b In a double-blind design, neither the experimenters (Rosenthal and Jacobson), nor the
subjects (the teachers) would have known the children’s ‘classification’. As the experimenters
were using deception to influence teachers’ expectations, there would be no point in
controlling the self-fulfilling prophecy by their (Rosenthal and Jacobson) being ‘blind’.
Learning Activity 8
Review questions: suggested answers
1 An experiment seeks to establish cause and effect. This is done by controlling the variables
of interest in a systematic way, and by minimising the influence of variables other than those
under study.
2 Variable: any factor that can change (vary) in amount or kind over time.
Independent variable: a variable in an experiment that is systematically manipulated,
changed or varied in some way by the experimenter, in order to measure its effect on the
dependent variable.
Dependent variable: a variable in an experiment that shows the effects of the independent
variable. It is a response observed or measured, and which changes as a result of the
manipulation of the independent variable.
Extraneous variable: a variable in an experiment other than the independent variable that can
cause a change in the dependent variable and therefore affect the results of the experiment in
an unwanted way.
PAGE
26
Psychology VCE Units 3 & 4
Research methods in psychology
© Macmillan Education Australia 2005. Unauthorised copying prohibited.
3 When experimenters manipulate the independent variable, they expect it to cause the
dependent variable to change. This is cause and effect. The manipulation is planned before
the experiment so that its effect on the dependent variable is predicted.
4
5 a The IV is new information learned. The DV is the rate and amount of forgetting.
b Possible extraneous variables include: participants’ age, intelligence, memory skills,
experience with nonsense words.
c The experimenter needs to ensure that groups in the experiment are as similar as
possible. For example, the experimenter needs to make sure that each group contains the
same profi le of participant ages, intelligence, memory ability and experience in this type
of setting. Intelligence and memory may require some preliminary testing, before the
experimenter randomly allocates the participants.
Learning Activity 13
Review questions: suggested answers
1 Researchers use a hypothesis as a tentative and testable prediction of the relationship
between two or more variables. It outlines the relationship so that the researcher can design
a study to support or refute the prediction.
2 Operational hypothesis: a hypothesis used in research that states how the variables under
study will be observed, manipulated and measured, as well as the population that has been
sampled.
3 An example follows for each of the concepts listed:
Forgetting: the number of nonsense words remembered an hour after the 15-word list was
studied for three minutes.
Aggression: the number of ‘angry’ words used in a piece of creative writing 500 words in
length.
Crowding: the number of rats in a cage 1-cubic metre in volume.
Anxiety: percentage of heart rate increase in subjects required to complete complex
numerical calculations within a limited time.
Relaxation: percentage of heart rate decrease in subjects after a one-hour massage.
Stress: the score obtained by a subject on a stress-rating scale (the Holmes and Rahe Social
Readjustment Scale) after a half-hour interview.
Independent variable Dependent variable
a Receiving reward for doing homework
(or not)
Amount of time spent studying
b Person in love (or not) Measure of how that person is perceived
c Carrots eaten (or not) Measure of night vision
d Baby picked up immediately it cries (or not) Amount of crying when alone (in future)
e Salary range Measure of job satisfaction
PAGE
35
Psychology VCE Units 3 & 4
Research methods in psychology
© Macmillan Education Australia 2005. Unauthorised copying prohibited.
4 An example operational hypothesis is given for each experimental question:
a Subjects required to perform complex numerical calculations after learning a list of 15
nonsense words will remember less words at testing an hour later than subjects who read
a novel.
b Rats living in cages containing 25 rats will bite or scratch other rats more frequently when
observed for an hour each day, than those living in identical cages containing fi ve rats.
c Subjects who undergo ten one-hour relaxation-training sessions over a fi ve-week period,
will be less stressed on the Holmes and Rahe SRS than those without the training.
5 A conclusion is a decision or judgment about what the results obtained from an investigation
mean. Unless terms in a hypothesis have been operationalised, the researcher’s conclusions
cannot be meaningful. For example in question 4b, if the researcher simply states ’crowding
increases aggression’ other scientists may point out that crowding needs defining, as does
aggression. Furthermore it might be that variables other than the IV are responsible for the
results. But this cannot be established unless the variables in the hypothesis have been
operationally defi ned.
Learning Activity 15
Review questions: suggested answers
1 Statistically significant means that the results obtained in a study are unlikely to be due to
chance (at an acceptably low level).
2 The p value is a probability value that shows the statistical level at which chance is likely to
have operated to produce the results of a research study.
3 p0.001 means that the probability that the results obtained in the study were due to chance
(and not caused by the IV) are one in one thousand or fewer.
p0.01 means that the probability that the results obtained in the study were due to chance
(and not caused by the IV) are one in one hundred or fewer.
p0.10 means that the probability that the results obtained in the study were due to chance
(and not caused by the IV) are one in ten or fewer.
4 a Of the values listed in question 3, p0.001 is the most significant. This means that chance
is less likely (one chance in a thousand) to have played a role in the results of the research
than either of the other levels of significance.
b Of the values listed in question 3, p0.10 is the least significant. This means that chance
is more likely (one chance in ten) to have played a role in the results of the research than
either of the other levels of significance.
5 If the p value obtained was not 0.05, then the probability that the results of my study were
due to chance would be too high, and I would be unable to have my hypothesis supported.
I would have to conclude that the results might have been due to chance and not the
independent variable.
PAGE
45
Psychology VCE Units 3 & 4
Research methods in psychology
© Macmillan Education Australia 2005. Unauthorised copying prohibited.
PAGE
47
Learning Activity 16
Review questions: suggested answers
1 After results are analysed a judgment as to whether the hypothesis will be supported or
rejected must be made.
2 a A conclusion is a decision or judgment about what the results obtained from an
investigation mean.
b In drawing conclusions from the results of a study, the experimenter must be confident
that any change in the dependent variable was due to the independent variable and not
due to extraneous variables operating during the study. The researcher must be cautious
to say that the hypothesis is supported, but never proven, as other factors may be at work
in a research situation.
3 a A generalisation is a conclusion made about whether the findings of a study can be applied
more widely, from the sample in the study, to the population from which it was drawn.
b The researcher must be cautious in generalising from sample to population. Consideration
must be given to: whether the sample was representative of the population, potential
extraneous variables, the nature of the sample and the research question being
investigated. Any generalisation must be based on the actual results obtained.
4 A conclusion is a judgment about what the results obtained from a study mean. A
generalisation is a judgment about whether the results from the sample can be applied
more widely (to the population from which the sample was drawn).