Transcript Template

RESEARCH METHODS
CORRELATIONAL
METHOD
G541 PSYCHOLOGICAL INVESTIGATIONS
CHECKLIST: Correlation
 Describe the key features of the correlational method
 Identify & describe what a positive, negative and zero correlation is.
 Evaluation the correlational method
 Be able to draw and label a scattergraph, showing the relationships between
two variables.
 Be able to interpret information shown on a scattergraph.
 Identify the variables either as represented on a scattergraph or by drawing
and labelling a scattergraph.
 Discuss the reliability and validity of scattergraph.
 Draw conclusions from scattergraph.
ACTIVITY 1
Worksheet 1: KEY WORDS
Complete the key terms related to this topic
You can use the resources and internet to help
Each definition should be at least two sentences long
You should use these terms where appropriate in your responses to
exam questions
EXAMPLE ESQ: June 2012
Psychologists conducted a study to investigate if there is a correlation
between personality and length of mobile phone text messages. Twenty
students aged 16-19 from one AS Psychology class attending a college In
London were used. Personality was assessed by asking the participants
to rate themselves using a scale of 1 (very Introvert - shy) to 10 (very
extrovert - outgoing). The average number of words used in a text
message over a period of one week was obtained from their phones.
1.
2.
3.
4.
5.
Outline one strength and one weakness of the sample used in this
study. (6)
Suggest an appropriate alternate hypothesis for this study. (4)
Outline one strength and one weakness of the way personality was
measured in this study. (6)
Explain what is meant by a negative correlation. (2)
Describe how data was presented in a scatter graph. (2)
TOTAL: 20 MARKS
ACTIVITY 2
Worksheet 2: Summary of the Correlational Method
Outline key features of the correlational method
Identify ethical issues related to the correlational method
Outline 3 strengths of the correlational method
Outline 3 weaknesses of the correlational method
KEY FEATURES: Correlation
Correlation is not a method of data collection but a data-analysis
technique. It is used in studies that are not experimental, i.e.
cause and effect cannot be established. It enables relationships
between variables to be established but not cause and effect.
 Correlation is a data-analysis technique, not a method of data collection
Correlations are relationships between variables
Correlations can be positive or negative
When a correlation is negative the values of one variable increases as the
other decreases.
When a correlation is positive the values of both variables increases or
decrease together.
Correlations are shown by drawing scattergraphs that show the
relationship between participants‘ score/measurements on both variables.
OVERVIEW: Correlation
Nature & Use
Advantages
Co-variables examined for positive, negative or
zero association.
•Allows study of hypotheses that cannot be
examined directly
•More data on more variables can be collected
more quickly that in an experiment set-up
Disadvantages
•Interpretation of results is difficult
•Cause and effect cannot be established
•Direction of causality is uncertain
•Variables other than one of interest may be
operating
Ethical Issues
Misunderstanding of findings because causal
relationship cannot be established
RESOURCES: Correlation
• Internet
• PowerPoint
• Exam Style Questions (ESQ)
CORRELATION
there will be an effect of x on y
Experimental (alterative) Hypothesis
Definition A statement of the relationship between variables
Reasons for An alternative to the null hypothesis
using (accept/reject)
there will be no effect of x on y
Null Hypothesis
Definition An assumption that there is no relationship
(difference, association, etc) in the population from
which a sample is taken with respect to the
variables being studied.
ACTIVITY 3
Worksheet 3: Generate Hypothesis
ACTIVITY
1. Identify the independent variable (IV) and the dependent
variable (DV) from each hypothesis.
2. Identify whether your hypotheses are one tailed or two tailed
(remember one-tailed hypothesis predicts the direction of the
effect of the IV on the DV, whereas a two-tailed hypothesis does
not).
3. Write a null hypothesis for each of the experimental
hypotheses.
HYPOTHESIS: Correlation
Generate a hypothesis for each of the following:
What are the effects of caffeine on attention and
concentration?
What are the effects of stress on sleep?
What are the effects of ....
The relationship between aggressive behaviour and
watching aggressive TV
The relationship between car speed and accidents
The relationship between rainfall and hosepipe bans
The relationship between hours of sunshine and time
spent on the beach
DATA: Correlation Co-efficent
A correlation coefficient is a mathematical measure of the
degree of relationship between sets of data. Once caculated, it
will have a value between -1 and +1:
• A PERFECT POSITIVE CORRELATION, indicated by +1, is where as
variable X increases, variable Y increases.
• A PERFECT NEGATIVE CORRELATION, indicated by -1, is where as
variable X increases, variable Y decreases.
Analysing correlational data
• Data can be plotted as points on a scattergraph. A line of best fit is
then drawn through the points to show the trend of the data.
• If no line of best fit can be drawn, there is no correlation.
Scattergraph
Null Hypothesis
Definition An assumption that there is no
relationship (difference,
association, etc) in the
population from which a sample
is taken with respect to the
variables being studied.
there will be no effect of x on y
EVALUATION: Correlation
Strengths
Correlation is a useful tool in psychology as it allows use to
measure the relationship between variables which it would
be difficult or unethical to manipulate experimentally. For
example we might be interested in investigating the
relationship between reported stress and ill health. It would
be impractical and unethical to manipulate stress or health.
However, it is possible to correlate self-reported levels of
stress with health data in order to establish whether there is
a relationship between the two.
Weaknesses
The major problem with correlational evidence is that
correlation does not imply causation. In other words, just
because two variables are correlated does not mean that one
of the has cause the other to change.
PROCEDURE: Overview
5-7 marks




Good description of procedure
Good evaluation of procedure
2 strengths
2 weaknesses
Describe (4 marks)
•Type
•Timing (20 min)
•Who
•Location
•When (time of day)
•IV/DV
8-10 marks

In-depth description of procedure,
including use of specialist terms
 In-depth evaluation of procedure
 3+ strengths
 3+ weaknesses
 Good use of grammar and limited
spelling mistakes.
Evaluate (6 marks)
•Reliability
•Validity
•Ethics
PROCEDURE: Plan
1.
2.
3.
4.
What the researcher is going to do step by step.
If it’s an observational method- what behaviour is going to be observed?
Have you classified the behaviour and created a coding system? Have all
the observers been chosen and given training on what behaviour to
observe and record? How you chosen where the observation in going to
be?
Don’t forget your key terms- i.e. what type of experiment is it? - The
strengths and weaknesses of that experiment type? Sampling methodstrengths and weaknesses of your sampling method and anything which
might affect your sample (Cohort effect). Single Blind/Double Blind
procedure? Any type of control method such as counterbalancing for
repeated measures design? What type of design in it? Inter rater
reliability? Ecological Validity? Ability to generalise?
How about any ethical issues which might need to be considered for the
study? How might they affect the results? How might you deal with
them? (Remember-brief/debriefing for a laboratory experiment?)
Remember- relate all these to the experiment in question. Responses
need to be in context. If the experiment is a laboratory experimentinclude factors that affect laboratory experiments such as low Ecological
validity which means it’s difficult to generalise outside a lab setting.
PROCEDURE: Correlation
1.
2.
3.
4.
5.
6.
7.
8.
9.
Decide aim and research question & hypothesis
Identify research method being used
Identify variables
Plan procedure: obtain ethics approval, outline how
you will carry out this research
Possibly run pilot study in order to check feasibility
Outline details of how you will collect data
If, appropriate, thank and debriefed pts
Analyse data, produce findings and draw
conclusions
Write report of practical investigation
ACTIVITY 4
Worksheet 4: Exam Style Questions (ESQ)
Complete the following ESQ for correlation
Example ESQ: June 2012
Scenario 1: Coffee & Reaction time
Scenario 2: Age & Physical Recreation
Scenario 3: Monthly income & mobile phone usage
Scenario 4: Stress levels & Hrs viewing TV
EXAMPLE ESQ: June 2012
Psychologists conducted a study to investigate if there is a correlation
between personality and length of mobile phone text messages. Twenty
students aged 16-19 from one AS Psychology class attending a college In
London were used. Personality was assessed by asking the participants
to rate themselves using a scale of 1 (very Introvert - shy) to 10 (very
extrovert - outgoing). The average number of words used in a text
message over a period of one week was obtained from their phones.
1.
2.
3.
4.
5.
Outline one strength and one weakness of the sample used in this
study. (6)
Suggest an appropriate alternate hypothesis for this study. (4)
Outline one strength and one weakness of the way personality was
measured in this study. (6)
Explain what is meant by a negative correlation. (2)
Describe how data was presented in a scatter graph. (2)
TOTAL: 20 MARKS
Exam Style Questions: Correlation
Scenario 1
A researcher decided to investigate whether there is a relationship
between how much coffee people drink at breakfast and their
reaction time. He anticipated that the findings would show a
negative correlation
1a. Describe the term ‘negative correlation’ in relation to this study (2)
1b. Formulate an appropriate alternative hypothesis for this investigation (2)
2a. Identify two extraneous variables that could influence the findings of this
study (2)
2b. Outline how one extraneous variable could be controlled in this
investigation (2)
3a. Describe an appropriate sampling technique that could be used to gather
participants for this study (2)
4. Outline how the researchers could have conducted this study (8)
1
Age Range
Mean time spent doing
physical activity PW
18-25
120
26-35
100
36-45
30
46-55
90
55-65
75
66-75
60
76-80
40
Scenario 2
An occupational therapist wanted to
investigate whether there is a relationship
between age and physical recreation. She
therefore advertised in a local newspaper
for participants between the ages of 1880yrs to contact her, so she could send
them a lifestyle questionnaire to
complete. A critical question in the
questionnaire measured the average time
spent each week by the participant doing
some form of physical activity, and there
was a box at the top of the questionnaire
in which the participant was asked to
state their age.
1a. Sketch a scattergraph to show the findings of this study (3)
1b. Draw two conclusions from this scattergraph (4)
2a. Describe the sampling technique used in this study (2)
2b. Suggest one strength of using this sampling technique in this study
3a. Describe one way in which time spent doing physical activity per week could have been measured
in this study (3)
3b. Describe one weakness of your suggested way of measuring participation in physical activity (2)
4. Describe one practical problem the occupational therapist may have encountered with this study (4)
2
Exam Style Questions: Correlation
Scenario 3
A psychologist wants to investigate whether there is a correlation
between an individual’s monthly earnings/income and the amount
of money they spend each month on mobile phone usage.
1a. Describe the term ‘correlation’ in relation to this study (2)
1b. Formulate an appropriate hypothesis for this study (2)
1c. Indentify the two variables being measured in this study (2)
2. Describe one ethical issue the psychologist needs to consider in
relation to this study and suggest how it might be managed (4)
3. Describe an appropriate procedure for this study (10)
3
Stress
140
120
100
80
Stress
60
40
20
0
0
5
10
15
Scenario 4
A researcher decided to
investigate the relationship
between perceived stress
levels and the amount of time
spent watching television. He
first asked participants to
complete a questionnaire to
assess stress levels and then to
estimate how many hours of
television they watched each
day.
1a. Describe one strengths of correlation (2)
1b. Describe one weakness of correlation (2)
2a. Describe the correlation shown in the scattergraph (2)
2b. Suggest one conclusion that could be drawn from this scattergraph (2)
2c. Sketch an appropriate table, showing the findings from this investigation (4)
3a. Describe one disadvantage of using a questionnaire to measure stress levels (2)
3b. Suggest an alternative way stress levels could have been measured in this study (2)
4. Briefly discuss the issue of validity in relation to this investigation (4)
4