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Research Methods
It is actually way more exciting
than it sounds!!!!
Why do we have to learn this
stuff?
Psychology is first and foremost a science.
Thus it is based in research.
Be aware however of two hurdles that tend to skew our
logic when we research
Hindsight Bias
• The tendency to
Monday Morning
Quarterbacking!!!
• Consider findings to be
Example:
Overconfidence
• Overconfidence –
• 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!!!)
Overconfidence
“There
is no reason for anyone to have a computerin their home.” (Ken Olson, president
of Digital Equipment Company, 1977)
“Heavier-than-air flying machines are impossible.”(Lord Kelvin, British mathematician,
physicist, and president of the British Royal Society, 1895)
“Reagan doesn’t have the presidential look.”(United Artists executive when asked
whether Ronald Reagan should be offered the starring role in the movie The Best
Man, 1964)
“A severe depression like that of 1920–1921 is outside the range of probability.”
(Harvard Economic Society, Weekly Letter, November 16, 1929)
“Man will never reach the Moon, regardless of all future scientific advances.” (Lee
DeForest, inventor of the vacuum tube, 1957)
The Scientific Attitude
• Three main components
Critical Thinking
• Critical Thinking –
– “Smart thinking”
– Four elements
• Examines
• Detects
• Evaluates
• Assesses
– Empirical Approach
Scientific Method
Theory –
• Often starts as an hypothesis
• Developed through repeated
observation and testing
• Example:
Hypothesis –
• Usually written in an If/Then
statement
• Explains what you expect will
happen
• Example:
Hypothesis Practice
• A researcher is evaluating the effectiveness of
a new physical education program for
elementary school children. The program is
designed to reduce competition.
• There is some evidence to suggest that
participation in class can have an effect on
human memory. A researcher plans to use a
standardized AP Psych exam to evaluate the
effects of class participation.
3Types of Research
• Descriptive
• Correlational • Experimental
3 Types of Descriptive Research
• The Case Study
• The Survey
• Naturalistic Observation
Case Studies
•
• Provides oppty to study unusual
cases in depth
• Offers suggestions for further
study
• Results often can’t be
• Can’t establish
Example: The ideal case
study was John and Kate.
Really interesting, but are
they typical of all families
Case Study Methodology
– Methodology
• Gather data from one
person (or small group)
through:
Naturalistic Observation
•
• Do not manipulate
the environment.
• May be done when it
is not ethical to
manipulate variables
• Does not show
Example: Jane Goodall’s
research on chimpanzees
Survey
• Gather Data –
• Personal facts
– Behaviors
– Attitudes
– Opinions
Survey Method
Method:
•Questionnaire
•Interview
•
Example:
1.On ave. how many hours do you study per night?
2.What is your grade point ave?
Conducting a Survey
• Population • Example:
• Random Sampling –
• Ensures that the participants are
• Helps avoid false generalizations
• Example:
Survey Method: The Bad
• Low Response Rate
• Response Bias/social
desirability bias –
How accurate would a survey be
about the frequency of diarrhea?
• Wording Effects –
Wording Effects
• Do you think it is •
important for
America to
provide aid to
the needy?
• Should the
government not
allow televised
cigarette ads?
Think Pair Share
1. A researcher wants to investigate people's
attitudes toward violence on television.
Explain which of the following research
methods the researcher should use and why:
case study, survey, or naturalistic
observation.
2. A researcher wants to investigate sharing
behaviors of young children. Explain which
research method the researcher would use
and why. Provide a brief explanation on how
the research would be conducted.
Correlational Method
• Correlation -
– Measures how well one variable
predicts the other
– Used when ethics prohibit
experimentation
• Can be efficient
• Can make predictions
• Can use pre-existing or archival
data
• Make it difficult to assess the
impact of a third variable
• Does not show
As more ice cream is eaten,
more people are murdered.
Does ice cream cause murder,
or murder cause people to eat
ice cream?
Results of Correlational
Studies
Positive Correlation
• The variables go in
Example:
Negative Correlation
• The variables go in
Example:
Correlation Coefficient
• Correlation Coefficient • Range is from -1 to +1
– The relationship gets weaker the
closer you get to
– (+) tells you the variables
– (-)tells you the variables are
– Scatterplot –
– shown as a graphed cluster of dots
Which is a stronger
correlation?
• -.13 or +.38
• -.72 or +.59
• -.91 or +.04
Which of the following would be a
negative correlation, and which
would be a positive
correlation?
Education and years in jail
Weight and hours of TV watched
Education and income
Holding babies and crying
Food and calories ingested
Correlation
The table below lists the scores of eight research participants on a test to
measure anxiety, as well as the typical number of cigarettes each person
smokes daily. Scores on the anxiety test can range anywhere from a low of 0
(indicating very low anxiety) to a high of 30 (indicating very high anxiety).
Research
Participant
1
2
3
4
5
6
7
8
Anxiety
Cigarettes
Test Score____________
8
11
9
3
15
11
14
16
21
26
12
10
22
24
17
18
Construct a scatterplot to represent the correlation between smoking and
anxiety. Describe the direction of the correlation and give two possible
explanations for it.
Correlation
Illusory Correlations
• Illusory Correlation
Think Pair Share
• Speaking at a college graduation ceremony, Professor
Robson compared college graduates with adults who
are less educated. She correctly noted that college
graduates pay more taxes, vote more frequently,
engage in more volunteer activities in their
communities, and are less likely to go to jail than
less-educated adults. The professor concluded that
colleges obviously do great things for society. How
might you reasonably challenge the way the
professor reached her conclusion?
Experimental Method
• Experiment –
•
•
•
•
Advantages:
Shows
Can verify results
Can eliminate bias
• Disadvantage:
Smoking causes health issues.
Theory
• Theory - An
explanation that
organizes
observation and
predicts behaviors
or events
• A hunch
• Example:
Hypothesis
• Hypothesis -
• Example:
Operational Definitions
• Operational Definition –
• Example:
Participation
• Meaning of hypothesis
• measure a variable
• Must be clear and
precise
• Must be
• Allow experiment to be
Higher Score -
Independent Variable
• Independent Variable
- Whatever is being
manipulated in the
experiment.
If there is a drug in an
experiment, the drug is
almost always the
independent variable.
Example:
Dependent Variable
• Dependent Variable –
• It is dependent on the
independent variable.
The dependent variable
would be the effect
of the drug.
Example:
Hypothesis and Operational Definitions
• Study: A scientist wants to study whether people
who make more money are happier
• Identify:
– Hypothesis
– Operational Definitions
• IV
• DV
• Study: A scientist wants to study whether or not
people who drink become more aggressive. Identify
the following:
– Hypothesis
– Operational Definitions
• IV
• DV
Assignment
• Random Assignment
–
– Minimizes differences between
two groups
– Different than Random Sample
– Reduces the impact of
• Experimental Group –
• Control Group –
• Examples:
Experimental –
Control group –
Beware of
Confounding Variables
• Confounding Variable –
• Confounds often arise
due to differences
between the groups that
exist before the
independent variable is
imposed!
Examples:
2 important confounding
variables
• Experimenter Bias -
• Example: • Placebo effect –
• Example:
Double-blind Procedure
• Double Blind –
• Minimizes
Replication
• Replication –
• What helps the
researcher to insure the
study can be replicated?
Quasi-experimental
• Quasi-experimental
• Used to study
differences
between:
–
• Confounding
variables so no cause
and effect
Controlled Observation
• Controlled
Observation –
– Conditions are
contrived by
researcher
– Independent and
dependent variable
– Does not show cause
and effect
• Early Psych
Research
Think Pair Share
• Design an experiment to test whether alcohol
consumption influences people's tendency to
become socially aggressive. In your experimental
design, identify the following experimental
elements and procedures: hypothesis, random
sampling, random assignment, experimental
group, control group, independent variable, and
dependent variable.
Statistics
• Recording the
results from our
studies.
• Must use a common
language so we all
know what we are
talking about.
Descriptive Statistics
• Descriptive Statistics –
Frequency Polygon
Frequency Histogram
–
• Examples:
Measures of Central Tendency
• Mode • Mean • Median -
Central Tendency
• Mean, Median and Mode.
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 $_______________________
The mean salary also looks good at about $________________
But the mode salary is only $___________________________
Watch out for extreme scores or outliers.
____________________is a better measure
than the mean when there are extremes/outliers
Normal Distribution
• In a normal
distribution, the
Examples:
Distributions
• Outliers skew
distributions.
• Positive Skew –
• Mean is higher than
median, so median better
measure of central
tendency
• Negative Skew –
• Mean is lower than
median, so median betterIf most students scored well on a
measure of central
test, what would the distribution look
tendency
like?
If most students scored poorly?
What does the data tell us?
Measures of variability
• Range:
• Standard Deviation:
• The higher the variance or SD, the more
spread out the distribution is.
• Do scientists want a big or small SD?
• Variance - The average of the squared
differences from the mean
Shaq and Kobe may both
score 30 ppg (same mean).
But their SDs are very
different…meaning?
Calculating Standard Deviation
Step 1 – calculate the mean –
add all of the raw scores and
divide by the # of scores
Step 2 – calculate the deviation
from the mean by
subtracting each of the raw
scores from the mean
Step 3 – square the deviation
from the mean for each
score
• Step 4 – Sum the squared
deviations
• Step 5 – divide the sum of
the squared deviation by the
number of scores and find
the square root
Calculating the Standard
Deviation
Calculating the Standard Deviation
your turn
Scores – 10, 3, 7, 8, 7
Step 1 – calculate the mean – add
the all of the raw scores and
divide by the # of scores
Step 2 – calculate the deviation
from the mean by subtracting
each of the raw scores from the
mean
• Step 3 – square the deviation
from the mean for each score
• Step 4 – Sum the squared
deviations
• Step 5 – divide the sum of the
squared deviation by the number
of scores and find the square
root
Variance
• Variance - The average of
the squared differences
from the Mean.
• = Standard Deviation2
• Tells you the same thing as Standard
Deviation—how consistent/reliable
the data is
• Example:
Standard Deviation = 5
Variance =
• *if you know the variance, how can
you calculate the standard deviation?
Scores
• Z Scores –
• Observation – Mean
Standard Deviation
• 10-15 = -1
5
• Equals 0 at the mean
• A positive z score =
Example: If John scored a 72 on a test
with a mean of 80 and a standard deviation•
of 8, John’s z score would be?
negative z score =
Normal Distribution
What is the probability an observation is less than the
z score or more than the z score?
Normal Distribution
Calculating the probability that scores are
above or below the mean
Step 1 – calculate the mean
Step 2 - calculate/find the standard deviation
or variance. If you only have the variance you
must calculate the standard deviation
Step 3 draw a normal distribution curve and
find the scores for each standard deviation
from the mean and place them on the graph
Step 4: calculating the % of students who
scored within a range of scores by finding the
corresponding scores on the curve, then add
the percentages from each standard
deviation.
Inferential Statistics
• Inferential Statistics - The purpose is to
discover whether the finding can be
• Statistical Significance – the observed
difference between the means of the
experimental and control group
• Measured by P-value= .05
– 5% likely the results are due to chance or
– 95% confidence level the results are due to the
independent variable
– You can apply the findings to the population
•
What does a p-value= .80 mean?
Statistical Significance
Key Ideas
• The bigger the difference between groups the less
likely it’s due to chance (regardless of sample size)
• Sample size matters. This is known as the "law of
large numbers."
– The larger the sample size, the smaller an
observed difference has to be in order to be
statistically significant.
– The smaller the sample size, the larger an
observed difference would have to be in order to
be statistically significant.
– Small sample, small difference not likely to be
statistically significant
Descriptive vs. Inferential Statistics
• Descriptive
• Inferential
– used to describe summarize a – Help researches draw
conclusions from data
data set
– Statistical Significance
– Make use of averages
• Mean
• Median
• Mode
– Address dispersion – how
widely the individual data
points are likely to be from
the mean
• Standard Deviation
• Variance
• P < .05
– Answers:
• Did the independent
variable cause changes in
the dependent variable?
• Should the Hypothesis be
supported or rejected?
• Can I apply my findings to
the general population?
APA Ethical Guidelines for
Research
• IRB• Both for humans and
animals.
Animal Research
•
•
•
•
Clear
Treated
Acquired
Least
Human Research
Milgram’s Study
• Hypothesis:
• Population
• Sample
• IV
– Op Def:
• DV
– Op Def:
• Random Assignment:
Milgram’s Experiment
• Criticized for
•
of
participants followed
the orders to the
maximum shock level
Milgram’s Experiment
• Obedience High
• Obedience Lower