Psychological Research Methods

1
Psychological Research Methods Statistics
Excavating Human Behaviors
2
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.

3
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?
4
Overconfidence

• 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!!!)
5
Exercise Unscramble these Anagrams

• WREAT
• ETRYN
• GRABE

6
Anagram Solutions

• WREAT --- WATER
• ETRYN --- ENTRY
• GRABE --- BARGE

7
The 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." 

8
Applied 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.
9
Psychological 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

10
The 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).

11
The 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.

12
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
• 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.

13
Research Methods Terminology
14
Hypothesis

• 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.

15
Independent 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.

16
Dependent 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.

17
Operational 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?

18
Selecting 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

19
Key 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

20
Methods 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?
21
The 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)

22
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?
23
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

What are the benefits and detriments of
Naturalistic Observation?
24
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?
25
Types 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.
26
Correlation 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.

27
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.

• Which is a stronger correlation?
• -.13 or .38
• -.72 or .59
• -.91 or .04

28
How to Read a Correlation Coefficient
29
(No Transcript)
30
Experimental Method
Smoking causes health issues.

• Looking to prove causal relationships
• Cause Effect
• Laboratory v. Field Experiments

Eating too many bananas causes
Constipation
31
Experimental 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.

32
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).

33
Experimental 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!!!

34
Beware 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.
35
Experimental 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.

36
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.

37
Practice 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

38
Descriptive 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

39
Measure 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.
40
Normal 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.

41
Distributions

• 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

42
Other 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.

44
Normal 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
45
(No Transcript)
46
Inferential 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.

47
Statistics 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

48
T-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

49
Research 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.

50
Research 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.

51
Mr. Q is Definitely an Outlier!
52
APA Ethical Guidelines for Research

• IRB- Internal Review Board
• Both for humans and animals

53
Animal Research

• Clear purpose
• Treated in a humane way
• Acquire animals legally
• Least amount of suffering possible

54
Human Research

• No Coercion- must be voluntary
• Informed consent
• Anonymity
• No significant risk
• Must debrief