Transcript Psychological Research Methods

Psychological Research
Methods & Statistics
Excavating Human Behaviors
Psychology & Research Methods
A “Scientific Attitude” is critical…
 Curiosity
– a passion to explore and understand.
 Skepticism – psychologists, like other scientists,
approach the world of behavior with curious
doubt. The are constantly asking two questions:
What does it mean? How do you know?
 Humility – an awareness and acceptance that we
may have to reject our own ideas or theories (if
they are proven wrong).
 Critical Thinking – a scientific approach
prepares/demands us to think “smarter”  to
examine assumptions, evaluate evidence, and
assess conclusions.
Hindsight Bias
The tendency to believe,
after learning the
outcome, that you knew it
all along.
 With 20/20 hindsight,
everything seems
obvious.

After the Chris Brown / Rihanna
incident….my husband said he
knew Chris Brown was a
violent kid!!! Did he really?
Overconfidence
We tend to think we know more than
we do.
 We tend to be more confident than
correct!
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82% of U.S. drivers consider themselves
to be in the top 30% of their group in terms
of safety
81% of new business owners felt they had
an excellent chance of their businesses
succeeding. When asked about the success
of their peers, the answer was only 39%.
(Now that's overconfidence!!!)
Exercise: Unscramble these Anagrams
WREAT
ETRYN
GRABE
Anagram Solutions
WREAT
--- WATER
ETRYN --- ENTRY
GRABE --- BARGE
The Barnum Effect
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It is the tendency for
people to accept very
general or vague
characterizations of
themselves and take
them to be accurate.
Barnum Effect Experiment - Subjects
take a bogus personality test that
produces a set of vague and even
self-contradictory statements such as
"you can be outgoing at times but at
times you can also be shy." When
put in the correct context people will
say that this analysis captures them
to a "T."
“There’s a sucker
born every minute.”
P.T. Barnum
Applied versus Basic Research
Applied Research
has clear, practical
applications.
 YOU CAN USE IT!!!
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Basic Research
explores questions
that you may be
curious about, but
not intended to be
immediately used.
Studying how
kissing changes
when you get
older is
interesting…but
that’s about it.
Research on therapies for drug addicts has
a clear purpose.
Psychological Research Methods
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Psychology is an experimental science.
Assumptions must be supported by evidence.
Psychologists use a variety of research methods
to study behavior and mental processes.
Psychologists follow the same general procedure
when conducting research:
1.
2.
3.
4.
5.
6.
Asking research questions
Forming hypothesis (hypotheses)
Testing the hypotheses
Analyzing the data (results)
And drawing conclusions
Eventually, replicating research
The Scientific Method
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Step 1: Forming research questions –
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Beginning with scientific curiosity and interest,
many research questions come from daily
experience, psychological theory, or common
knowledge.
Step 2: Forming hypotheses –
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A hypothesis is a predicted “answer” the question
(or in other words, “an educated guess”).
The Scientific Method
 Step 3: Testing hypotheses –
1. Once a hypothesis has been formed, it must be scientifically
tested and proved right or wrong.
2. This part of conducting research is the “actual” experiment.
3. Psychologists use a variety of methods to test hypotheses.
 Step 4: Analyzing Results –
1. Data is analyzed using statistics
2. The more data collected,
the more complex a task
it is to analyze.
The Scientific Method
• Step 5: Drawing Conclusions –
• Once the results have analyzed, a psychologists can draw
or make conclusions about his/her questions and
hypotheses.
• Step 6: Replication –
1. Even when a research study carefully follows proper
procedures, its findings might just represent a random
occurrence.
2. To confirm the results and conclusions of a research study,
the study must be replicated.
3. The study must be repeated and it must produce the same
or similar results as before.
4. If there are different results, then the findings of the first
study are questioned.
Research Methods Terminology
Hypothesis
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Expresses a
relationship
between two
variables.
A variable is
anything that can
vary among
participants in a
study.
Participating in class
leads to better
grades than not
participating.
Independent Variable
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Whatever is being
manipulated in the
experiment.
Hopefully the
independent
variable brings
about change.
If there is a drug in
an experiment, the
drug is almost always
the independent
variable.
Dependent Variable
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The dependent variable
would be the effect
of the drug.
Whatever is being
measured in the
experiment
It is dependent on
the independent
variable.
Operational Definitions
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Explain what you mean
in your hypothesis.
How will the variables
be measured in “real
life” terms.
How you
operationalize the
variables will tell us if
the study is valid and
reliable.
Let’s say your hypothesis
is that chocolate causes
violent behavior.
 What do you mean by
chocolate?
 What do you mean by
violent behavior?
Selecting Subjects
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Population – all members of a given
group (of study)
Sample – a subset of the population which
is representative of the whole population
Random Sample – a sample in which every
member of the population has an equal
change of being selected
Stratified Sample – a sample in which each
subgroup of the population is represented
proportionally to its size in the population
Key Research Terminology
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Using a random sample that represents the
whole population, a researcher can
generalize findings to the entire population.
CAUTION: Overgeneralization – is the
making of generalizations using
unrepresentative cases. It is easy to do but
typically erroneous.
False Consensus Effect: the tendency to
overestimate the extent to which others
share our beliefs and behaviors
Methods of Collecting Data
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Survey – commonly used in both descriptive and
correlational studies, questionnaire method sampling many
cases (individuals) in less depth
Case Study – the study of one or more individuals in great
depth, to inform about an entire population or sample
Testing – psychological tests are given to
measure certain mental processes, such as intelligence,
aptitude, or personality
The ideal case study is John
and Kate. Really interesting, but
what does it tell us about
families in general?
The Survey Method
 Used
in both descriptional and
correlational research.
 Use Interview, mail, phone, internet
etc…
 The Good- cheap, anonymous, diverse
population, and easy to get random
sampling (a sampling that represents
your population you want to study)
Survey Method: The Bad
 Low
Response
Rate
 People Lie or
just
misinterpret
themselves.
 Wording
Effects
How accurate would a
survey be about the
frequency of diarrhea?
Naturalistic Observation
Observing and recording
behaviors of an organism
in natural environment
 No control- just an
observer (do not
manipulate the
environment)
 This method does not
explain behavior but
describes it
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What are the benefits and detriments of
Naturalistic Observation?
Methods of Collecting Data
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Laboratory Observation – this research method
involves watching and recording behaviors of
organisms NOT in their natural environment BUT
in a laboratory setting.
Cross-sectional Studies – uses participants (subjects)
of different ages to compare how certain variables
may change over the life span.
Longitudinal Studies – use one group of
participants over a long period of time. This
method of study tracks the change over time of the
participants.
Correlational Research
 Detects
relationships between variables
 Does NOT say that one variable causes
another
There is a positive
correlation between ice
cream and murder
rates. As more ice
cream is eaten, more
people are murdered.
Does that mean that
ice cream causes
murder?
Types of Correlation
Positive Correlation
 The variables go in
the SAME direction.
Negative Correlation
 The variables go in
opposite directions.
Studying and
grades hopefully
has a positive
correlation.
Heroin use and
grades probably has
a negative
correlation.
Correlation vs. Cause & Effect
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Correlation coefficient is a statistical
measure of relationship (it reveals how
closely related two factors are or how
closely two factors vary together and thus
how well either one predicts the other).
Positive and negative correlations are
possible
A relationship does not mean causation!!!
• For example, watching TV violence positively
correlates with aggressive behavior; but does
not necessarily mean watching violence on TV
causes aggressive behavior.
Correlation Coefficient
A number that
measures the
strength of a
relationship.
 Range is from -1 to +1
 The relationship gets
weaker the closer you
get to zero.
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Which is a stronger
correlation?
 -.13 or +.38
 -.72 or +.59
 -.91 or +.04
How to Read a Correlation Coefficient
Experimental Method
Looking to prove
causal relationships
 Cause = Effect
 Laboratory v. Field
Experiments
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Eating too many bananas causes
Smoking causes
health issues.
Constipation
Experimental Research
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In an experiment, participants receive what is called
a treatment, such as a change in room temperature or
a new drug.
Then, psychologists carefully observe the
participants to determine how the treatment
influences their behavior.
Independent and Dependent
Variables
All research studies measure and
observe variables (factors), especially
experimental studies.
 In an experiment, the independent
variable is the factor that the
researcher manipulates (controls) so
that they can determine its effect on
the dependent variable.
 The dependent variable is the factor
that depends on the manipulated
independent variable(s).
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Experimental and Control Groups
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The experimental group is a group of participants who
receive the treatment or manipulated variable.
The control group is a group of participants who do not
receive the manipulated variable (instead a placebo of
sorts).
All other variables/factors are held constant (or equal)
for both groups (to try to isolate a cause and effect
relationship between independent variable(s) of interest
to the research psychologist and the dependent variable.
If the research psychologist fails to manage the ‘other’
variables (or hold them constant), they become
confounding variables. Confounding variables are
baaaaad!!!
Beware of
Confounding Variables
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If I wanted to prove that
smoking causes heart
issues, what are some
confounding variables?
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The object of an
experiment is to prove
that A causes B.
A confounding variable
is anything that could
cause change in B, that
is not A.
Lifestyle and family
history may also
effect the heart.
Experimental Method
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continued
Psychologists randomly place participants (subjects) into
one group or another.
– EXAMPLE: The effect of extracurricular activities on student’s
academic success.
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Once subjects are randomly placed into the control and
experimental groups, the researcher makes sure that all
other variables are the same for all students regardless of
group.
Using this grouping method in the experimental method is
called a controlled experiment.
The Placebo Effect
 In research studies and in our daily lives, our expectations
affect what happens to us.
 Feeling better simply because we expect to feel better
and for no other reason is an example of the placebo
effect.
 A placebo is a substance or treatment that has no effect
apart from the person’s belief in it.
Experimental Method
continued
Single-blind vs. Double-blind Studies
 In a single-blind study, participants do not
know whether they are receiving the
treatment (the manipulated independent
variable) or not. In other words, they do not
know if they are in the experimental group or
in the control group.
 This process avoids the placebo effect.
 In a double-blind study, both participants
and researchers are unaware of who has
placed in which group.
Descriptive Statistics
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Just describes sets
of data.
You might create a
frequency distribution.
Frequency polygons or
histograms.
Measure of Central Tendency
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Mean, Median and Mode.
Watch out for extreme scores or outliers.
Let’s look at the salaries of the
employees at Dunder Mifflen Paper
in Scranton:
$25,000-Pam
$25,000- Kevin
$25,000- Angela
$100,000- Andy
$100,000- Dwight
$200,000- Jim
$300,000- Michael
The median salary looks good at
$100,000.
The mean salary also looks good at
about $110,000.
But the mode salary is only $25,000.
Maybe not the best place to work.
Then again living in Scranton is kind
of cheap.
Normal Distribution
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In a normal distribution,
the mean, median and
mode are all the same.
The mean is the most
commonly used measure
of central tendency, but
its accuracy can be
distorted by extreme
scores or outliers.
Distributions
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Outliers skew
distributions
If group has one high
score, the curve has a
positive skew
(contains more low
scores)
If a group has a low
outlier, the curve has
a negative skew
(contains more high
scores)
Other measures of
variability
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Range: distance from
highest to lowest
scores.
Standard Deviation:
the variance of scores
around the mean.
The higher the
variance or SD, the
more spread out the
distribution is.
Do scientists want a
big or small SD?
Shaq and Kobe may both
score 30 ppg (same mean).
But their SDs are very
different.
Scores
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A unit that measures
the distance of one
score from the
mean.
A positive z score
means a number
above the mean.
A negative z score
means a number
below the mean.
Normal Distribution
Inferential Statistics
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The purpose is to
discover whether the
finding can be applied to
the larger population
from which the sample
was collected.
T-tests, ANOVA or
MANOVA
P-value= .05 for
statistical significance.
5% likely the results are
due to chance.
Statistics & Research Methods
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Null hypothesis: (H0) is a hypothesis (scenario)
set up to be nullified, refuted, or rejected
('disproved' statistically) in order to support an
alternative hypothesis
Type I error: the error of rejecting a null
hypothesis when it is actually true
Type II error: the error of failing to reject a null
hypothesis when the alternative hypothesis is the
true state of nature
T-test
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The t-test assesses whether the means of two
groups are statistically different from each other.
This analysis is appropriate whenever you want
to compare the means of two groups
www.graphpad.com/quickcalcs/ttest1.cfm
X = mean of group
Var = Standard deviation of group
N = number in sample
Research & Statistics Assignment 1
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Gather shoe size data from 10 females and 10
males, recording the shoe size of each.
Then calculate the measures of central tendency
(mean, mode, median) and graph the data set in
a frequency histogram and box-plot.
Find and discuss any outliers
Explain the gender difference, if one exists.
Research & Statistics Assignment 2
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Using the Research Question: How many pairs of
shoes do males and females own? Write a testable
hypothesis.
Next, gather data from 10 females and 10 males,
recording the number of shoes owned by each.
Ask your participants, “How many pairs of shoes do
you own?” and (obviously) record their answer and
gender.
Calculate the measures of central tendency and
standard deviation and test for differences between
means using a t-test. (use
www.graphpad.com/quickcalcs/ttest1.cfm to help you
calculate a t-score)
Write a brief conclusion about your results (at least 1
paragraph). Make sure you give an explanation for the
APA Ethical Guidelines for
Research
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IRB- Internal Review
Board
Both for humans and
animals
Animal Research
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Clear purpose
Treated in a humane
way
Acquire animals
legally
Least amount of
suffering possible.
Human Research
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No Coercion- must
be voluntary
Informed consent
Anonymity
No significant risk
Must debrief