Transcript Research Methods

The Scientific Attitude
 3 main components
 Curiosity
 Skepticism
 Humility
The Scientific Method
 A way of rigorously testing ideas against objective
observations.
 Psychology is a science because it uses the scientific
method to test ideas empirically.
The Scientific Method
 Empirical Investigation – The collecting of objective
information firsthand by making careful
measurements based on direct experience.
 This is the heart of the testing procedure in the scientific
method.
 To investigate a question “empirically” would mean to
collect evidence yourself.
The Goal of Psychological Science?
 To develop explanations for behavior and mental
processes… based on solid EMPIRICAL SCIENCE!
Theories
 In psychology, theories are explanations for behavior
and mental processes.
 Definition: A testable explanation for a set of facts or
observations.
 Different from a speculation or guess
The Steps of the Scientific Method
 Step 1: Develop a Hypothesis
 Hypothesis: A statement predicting the outcome of a
scientific study; a statement describing the relationship
among variables in a study.
 “Little Theory”
The Steps of the Scientific Method
 Step 1: Forming a Hypothesis (Cont.)
 Operational definitions – Specific descriptions of
concepts involving the conditions of a scientific study.
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Must be included in the hypothesis.
Used to check researcher bias.
Also allows others to REPLICATE the study
The Steps of the Scientific Method
 Step 2: Performing a Controlled Test
 Hypothesis must undergo a controlled test to determine
whether it passes or fails.
 Independent Variable – Condition that the experimenter
changes independently of all the other carefully
controlled experimental conditions.
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The STIMULI you are studying.
 Random Presentation must also occur.
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Change independent variable randomly so it is unpredictable.
The Steps of the Scientific Method
 Step 3: Gathering Objective Data
 Data- Information gathered by direct observation.
 Dependent Variable – The measured outcome of a study;
the responses of the subjects in a study.
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Comes from the assumption that the responses of participants
in an experiment depend directly on the conditions to which
they have been exposed.
The RESPONSE made by the participants in the experiement.
The Steps of the Scientific Method
 Step 4: Analyzing the Results and Accepting or
Rejecting the Hypothesis.
 Pretty self explanatory right???
 Have to take into consideration the probability of right
answers when guessing…
The Steps of the Scientific Method
 Step 5: Publishing, Criticizing, and Replicating the
Results.
 Often, people try to publish scientific research, but
before being published it must be critiqued and
criticized by experts.
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Fewer than 2% of papers on psychological research submitted
to journals actually get into print without major revisions.
 Some critics who are on the fence may attempt to
replicate the experiment.
Types of Psychological Research
 Experimental Method – Used to determine Cause and
Effect!
 Develop a research question
 Survey the literature (helps for hypothesis)
 Form Hypothesis
 Establish Independent Variable (Part that changes)
 Establish Dependent Variable (The measured outcome
of a study; the responses of the subjects in a study)
 Confounding or Extraneous Variable (Other things that
can affect the outcome).
Types of Psychological Research
 Experimental Method (Cont.)
 Ensure Controls (Ensure all groups in the experiment
are treated exactly the same).
 Choose Sampling / Subjects (Must be random to
represent population).
 Procedure
 Results / Statistics
 Discussion
Control Group vs. Experimental
Group
 Control Group – Serves as a standard against which
other groups can be compared.
 Experimental Group – The group that is manipulated
by variables in an experiment.
Types of Psychological Research
 Non Experimental Method
 Lack the control of Experimental Research Methods.
 Used in situations where it may be unethical to conduct
true experimental research.
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Ex. – Cancer research.
Ex Post Facto – Research in which we choose subjects based
on a pre-existing condition.
Types of Psychological Research
 Correlational Studies
 Mainly statistical in nature.
 Determine the relationship (or correlation) between 2
variables.
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Example – People who smoke are more likely to get lung
cancer.
Use something called the CORRELATION COEFFICIENT to
summarize the relationship between 2 variables in an
experiment.
Types of Psychological Research
 Correlational Studies (Cont)
 Correlation Coefficient
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Can range from a negative number as low as -1.0 to a positive
number as high as +1.0.
Positive Correlation
Negative Correlation
Zero Correlation
Types of Psychological Research
 Correlational Studies (Cont.)
 Zero Correlation = No relationship between the
variables.
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Example – There is a zero correlation between shoe size and
GPA.
Types of Psychological Research
 Correlational Studies (Cont.)
 Positive Correlation – Variables show a relationship in
which they vary in the same direction (as the values of
one variable increase, so do those of the other).
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Example – There is generally a positive correlation of about
+0.4 between SAT scores and college grades.
Types of Psychological Research
 Correlational Studies (Cont.)
 Negative Correlation – Variables show a relationship in
which they vary in the opposite direction (as the value of
one variable goes up, the value of the other variable goes
down).
 Example – A correlational study on anxiety shows a
correlation of -0.7 between anxiety and time spent
studying. In other words, more study is associated with
less anxiety.
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A negative correlation can still indicate a very strong
relationship.
Types of Psychological Research
 Surveys
 A quasi-experimental method in which questions are
asked to subjects.
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Questions cannot be skewed or biased toward a particular
answer.
Types of Psychological Research
 Naturalistic Observation
 Subjects are observed in their natural environment.
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Much less control in this
Key: Must be sure subjects are not aware they’re being
observed.
Types of Psychological Research
 Longitudinal Study
 One group of subjects is followed and observed for an
extended period of time.
 Good for investigating the long range effects of
something.
Types of Psychological Research
 Cross-sectional Study
 Study in which representative cross section of the
population is tested or surveyed at one specific time.
 Cohort-sequential Study
 Study in which a cross section of the population is
chosen and then each cohort is followed for a short
period of time.
 Both are similar to longitudinal studies.
Bias in Research
 Personal Bias
 The researcher allowing personal beliefs to affect the
outcome of a study.
Bias in Research
 Expectancy Bias
 The researcher allowing his or her expectations to affect
the outcome of a study.
Combating Bias in Research
 Double – Blind Study
 An experimental procedure in which both researchers
and participants are uninformed about the nature of the
independent variable being administered.
 Placebo involved to keep participants and researchers
from forming bias.
Ethics in Research
 Institutional Review Board – Group that reviews and
approves all research to ensure no ethical violations
take place.
 Deception – Allowed under certain circumstances.
 Participants must be debriefed afterward.
 Animal Research Studies
Organizing Research Data
 Descriptive Statistics
 Statistical procedures used to describe characteristics
and responses of groups of subjects.
Organizing Research Data
 Descriptive Statistics
 Measure of Central Tendency
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AKA – Averages
Help us locate the center of a set of measurements.
Organizing Research Data
 Descriptive Statistics
 Measure of Central Tendency has 3 forms
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Mean – The measure of central tendency most often used to
describe a set of data – calculated by adding all the scores and
dividing by the number of scores.
 Can be distorted by extreme scores.
Organizing Research Data
 Descriptive Statistics
 Measure of Central Tendency has 3 forms
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Median – A measure of central tendency of distribution,
represented by the score that separates the upper half of the
scores in a distribution from the lower half.
 The middle score.
 Not distorted by extreme scores.
Organizing Research Data
 Descriptive Statistics
 Measure of Central Tendency has 3 forms
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Mode – A measure of central tendency for a distribution,
represented by the score that occurs more often than any
other.
 Not effective when test groups are small.
Organizing Research Data
 Descriptive Statistics
 Measures of Variability
 Allows us to know how well the average represents the
distribution as a whole.
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That is, do most of the scores cluster closely near the average
or are they spread out widely.
Low Variability = All scores close to the average.
High Variability = Scores widely spread out.
Organizing Research Data
 Descriptive Statistics
 Measures of Variability
 Range – The simplest measure of variability, represented
by the difference between the highest and the lowest
values in a frequency distribution.
 Standard Deviation – A measure of variability that
indicates the average difference between the scores and
their mean.
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The larger the score the more spread out they are.
The smaller the score the closer together they are.
Organizing Research Data
 Inferential Statistics
 Statistical techniques used to assess whether the results
of a study are reliable or whether they might be simply
the result of chance.
 Often used to determine whether two or more groups
are essentially the same or different.
Organizing Research Data
 Inferential Statistics
 To ensure accurate statistics must be sure samples are
selected in an unbiased manner.
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Random Sample – Sample group of subjects selected by
chance.
 Not always practicable.
Representative Sample – A sample group obtained in such a
way that it reflects the distribution of important variables in
the larger population in which the researchers are interested.
 Age, income, ethnicity, and location all considered.
Organizing Research Data
 Inferential Statistics
 Significant Difference – Psychologists accept a difference
between the groups as “real,” or significant, when the
probability that it might be due to an atypical sample
drawn by chance is less than 5 in 100.
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Indicated by the notation p<.05.