Title: Psychological Research Methods
1Psychological Research Methods Statistics
Excavating Human Behaviors
2Psychology 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.
3Hindsight 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?
4Overconfidence
- We tend to think we know more than we do.
- We tend to be more confident than correct!
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!!!)
5Exercise Unscramble these Anagrams
6Anagram Solutions
- WREAT --- WATER
- ETRYN --- ENTRY
- GRABE --- BARGE
7The Barnum Effect
Theres a sucker born every minute. P.T. Barnum
- 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."
8Applied versus Basic Research
- Applied Research has clear, practical
applications. - YOU CAN USE IT!!!
- 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 interestingbut thats about it.
Research on therapies for drug addicts has a
clear purpose.
9Psychological Research Methods
- 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 - Asking research questions
- Forming hypothesis (hypotheses)
- Testing the hypotheses
- Analyzing the data (results)
- And drawing conclusions
- Eventually, replicating research
10The Scientific Method
- Step 1 Forming research questions
- Beginning with scientific curiosity and interest,
many research questions come from daily
experience, psychological theory, or common
knowledge. - Step 2 Forming hypotheses
- A hypothesis is a predicted answer the question
(or in other words, an educated guess).
11The Scientific Method
- Step 3 Testing hypotheses
- Once a hypothesis has been formed, it must be
scientifically tested and proved right or wrong. - This part of conducting research is the actual
experiment. - Psychologists use a variety of methods to test
hypotheses. - Step 4 Analyzing Results
- Data is analyzed using statistics
- The more data collected,
- the more complex a task
- it is to analyze.
12The 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
- Even when a research study carefully follows
proper procedures, its findings might just
represent a random occurrence. - To confirm the results and conclusions of a
research study, the study must be replicated. - The study must be repeated and it must produce
the same or similar results as before. - If there are different results, then the findings
of the first study are questioned.
13Research Methods Terminology
14Hypothesis
- 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.
15Independent Variable
- 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.
16Dependent Variable
- Whatever is being measured in the experiment
- It is dependent on the independent variable.
- The dependent variable would be the effect of the
drug.
17Operational Definitions
- 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.
- Lets say your hypothesis is that chocolate
causes violent behavior. - What do you mean by chocolate?
- What do you mean by violent behavior?
18Selecting Subjects
- 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 chance of being
selected - Stratified Sample a sample in which each
subgroup of the population is represented
proportionally to its size in the population
19Key Research Terminology
- 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
20Methods of Collecting Data
- 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?
21The Survey Method
- 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)
22Survey 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?
23Naturalistic 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
What are the benefits and detriments of
Naturalistic Observation?
24Correlational 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?
25Types of Correlation
- Negative Correlation
- The variables go in opposite directions.
- Positive Correlation
- The variables go in the SAME direction.
Studying and grades hopefully has a positive
correlation.
Heroin use and grades probably has a negative
correlation.
26Correlation vs. Cause Effect
- 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.
27Correlation 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.
- Which is a stronger correlation?
- -.13 or .38
- -.72 or .59
- -.91 or .04
28How to Read a Correlation Coefficient
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30Experimental Method
Smoking causes health issues.
- Looking to prove causal relationships
- Cause Effect
- Laboratory v. Field Experiments
Eating too many bananas causes
Constipation
31Experimental Research
- 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.
32Independent 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).
33Experimental and Control Groups
- 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!!!
34Beware ofConfounding Variables
- 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.
- If I wanted to prove that smoking causes heart
issues, what are some confounding variables?
Lifestyle and family history may also effect the
heart.
35Experimental Method continued
- Psychologists randomly place participants
(subjects) into one group or another. - EXAMPLE The effect of extracurricular activities
on students academic success. - 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 persons belief
in it.
36Experimental 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.
37Practice Identifying Independent Variable and
Dependent Variable
- In addition to finding the I.V and the D.V.,
identify - The experimental group/condition(s)
- The control group/condition
- A possible confounding variable
- Hint The third example has two
- experimental groups/conditions
38Descriptive Statistics
- Just describes sets of data
- You might create a frequency distribution,
frequency polygons or histograms - Measures of Central Tendency
- (1) Mean The average of all scores in a
distribution - (2) Median The central score in a
distribution (middle) - (3) Mode The score that appears most
frequently in a distribution -
39Measure of Central Tendency
- Mean, Median and Mode.
- Watch out for extreme scores or outliers.
Lets 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.
40Normal Distribution
- 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.
41Distributions
- Outliers skew distributions have a more
dramatic effect on the mean - If group has one high score, the curve has a
positive skew (contains more low scores) - Positively skewed the mean is higher than
the median - If a group has a low outlier, the curve has a
negative skew (contains more high scores) - Negatively skewed the mean is lower than
the median
42Other measures of variability
- 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. - Low SD indicates that the data points tend to
be very close to the mean - High SD indicates that data points are spread
out over a large range of values
Shaq and Kobe may both score 30 ppg (same
mean). But their SDs are very different!
43 Scores
- 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.
44Normal Distribution
Decker Story
Approx. 68 of scores in a normal distribution
fall within 1 standard deviation point of the mean
Approx. 95 of scores fall within 2 standard
deviation points of the mean
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46Inferential Statistics
- 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.
47Statistics Research Methods
- 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
48T-test
- 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
49Research Statistics Assignment 1
- 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 or box-plot for both the
female findings and the male findings. - Find and discuss any outliers
- Explain the gender difference, if one exists.
50Research Statistics Assignment 2
- 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 differences between the
gender.
51Mr. Q is Definitely an Outlier!
52APA Ethical Guidelines for Research
- IRB- Internal Review Board
- Both for humans and animals
53Animal Research
- Clear purpose
- Treated in a humane way
- Acquire animals legally
- Least amount of suffering possible
54Human Research
- No Coercion- must be voluntary
- Informed consent
- Anonymity
- No significant risk
- Must debrief