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Unit 2: Research Methods
Key Terms and Concepts
Hindsight Bias: the tendency to believe, after learning an outcome, that one would have foreseen it (also
known as the "I knew it all along" phenomenon)
Critical Thinking: thinking that does not blindly accept arguments and conclusions; rather, it examines
assumptions, discerns hidden values, evaluates evidence, and assesses conclusions
Theory: an explanation using an integrated set of principles that organizes observations and predicts
behaviors or events
Hypothesis: a testable prediction, often implied by a theory
Operational Definition: a statement of the procedures (operations) used to define research variables; for
example, human intelligence may be operationally defined as what an intelligence test measures
Replication: repeating the essence of a research study, usually with different participants in different
situations, to see whether the basic finding extends to other participants and circumstances
Case Study: an observation technique in which one person is studied in depth in the hoe of revealing
universal principles
Survey: a technique for ascertaining the self-reported attitudes or behavior of a particular group, usually by
questioning a representative, random sample of the group
Population: all the cases in a group being studied, from which samples may be drawn (note: except for
national studies, this does not refer to a country's whole population)
Random Sample: a sample that fairly represents a population because each member has an equal chance of
inclusion
Naturalistic Observation: observing and recording behavior in naturally occurring situations without trying
to control or manipulate the situation
Correlation: a measure of the extent to which two factors vary together, and thus of ow well either factor
predicts the other
Correlation Coefficient: a statistical index of the relationship between two things (from -1 to +1)
Scatterplot: a graphed cluster of dots, each of which represents the values of two variables; the slop of the
points suggests the direction of the relationship between the two variables; the amount of scatter suggests the
strength of the correlations (little scatter = high correlation)
Illusory Correlations: the perception of a relationship where none exists
Experiment: a research method in which an investigator manipulates on or more factors (independent
variables) to observe the effect on some behavior or mental process (the dependent variable); by random
assignment of participants, the experimenter aims to control other relevant factors
Random Assignment: assigning participants to experimental and control groups by chance, thus minimizing
preexisting differences between those assigned to the different groups
Double-blind Procedure: an experimental method where neither the participants nor the research staff know
whether one person got the treatment or the placebo
Placebo Effect: experimental results caused by expectation alone; any effect on behavior cased by the
administration of an inert substance or condition, which the recipient assumes is an active agent
Experimental Group: the group exposed to the treatment (to one version of the independent variable)
Control Group: the group that does not receive the treatment; serves as a comparison for evaluating the
effect of the treatment
Independent Variable: the variable being manipulated and whose effect is being studied
Confounding Variable: a factor other than the independent variable that might produce an effect in an
experiment
Dependent Variable: the outcome factor; the variable that may change in response to manipulations of the
independent variable; the variable being measured
Mode: most frequently occurring score(s) in a distribution
Mean: the average (add scores and divide by the number of scores that there are)
Median: the middle score in a distribution; half the scores are above it and half are below it
Range: the difference between the highest and lowest scores in a distribution
Standard Deviation: a computed measure of how much scores vary around the mean score
Normal Curve (normal distribution): a symmetrical, bell-shaped curve that describes the distribution of
many types of data; most scores fall near the mean (68% fall within one standard deviation of it, 95% fall
within two, and 98% fall within three)
Statistical Significance: a statistical statement of how likely it is that an obtained result occurred by chance
Culture: the enduring behaviors, ideas, attitudes, and traditions shared by a group of people and transmitted
from one generation to the next
Informed Consent: an ethical principle that research participants be told enough to enable them to choose
whether they wish to participate in an experiment
Debriefing: the post-experimental explanation of a study, including its purpose and any deceptions, to its
participants
Need for Psychological Science
 Hindsight bias and judgmental overconfidence show that we cannot rely on intuition and common sense.
Critical thinking must also be employed in order to perceive facts from nonsense.
Hind sight Bias
 The thought that once a person find out the outcome, that the person knew the outcome all along and
could have predicted it.
 Proves that we need psychological research
 Common sense describes what has happened more easily than predict what will happen
Overconfidence
 Thinking is limited
 Even when you are 100% sure about something, self prediction may change up to 15% of the time.
 When prediction becomes wrong, individual’s attempt the ‘I was close’ excuse
 Often leads to the overestimation of our potential.
Scientific Attitude
 Sometimes refutes skeptics
 Being skeptical but not cynical, open but not gullible
 Skeptical testing could separate the real facts
 Requires skepticism and humility
 Need to reject our own ideas
 Copernicus and Newton, are examples of people who used the scientific attitude
 Critical Thinking examines assumptions, discerns hidden values, evaluates evidence and assess’s
conclusion without blindly accepting arguments and conclusions.
Scientific Method
 Scientific Theory explains through principles that organizes and predicts behaviors or events.
 By organizing isolated facts, theory simplifies things.
 Connection of observed dots, we may discover a pattern
 Hypothesis is testable prediction, often started by a theory
 Research allows one to test or reject the theory
 Operational Definition is a statement of the procedures used to define research variables.
 Replication when a procedure could be repeated with different participants in different situations to see
whether the same result is found.
 A theory is successful if it links and organizes observed facts and if it implies hypothesis that offer
testable predictions and practical applications.
Case Study
 An observation technique in which one person is studied in depth in hope of revealing universal principles
 Case studies can suggest hypotheses for further study.
 Unrepresentative information can lead to mistaken judgments and false conclusions.
 Anecdotal stories may elevate the truth
 Does not work to find the general truths that cover individual cases
Survey
 Looks at many cases in less depth
 Asks individuals about their behaviors and opinions
 Answers depend on wording
 May use random sampling
Random Sampling
 False consensus effect is the tendency to overestimate the extent to which others share our beliefs and
behaviors
 Populations includes all the cases in a group from which samples may be drawn from a study
 Random sampling represents a populations because each member has an equal chance of inclusion
 Very large samples may be more reliable
 Basis of generalizing is from representative sample of cases
Naturalistic Observation
 Observing and recording behavior in naturally occurring situations without trying to manipulate and
control the situation
 Does not explain behavior, it describes it
 Robert Levine and Ara Norenzayan – compared pace of life
 Can be used with correlation research
Correlation
 When two traits seem to accompany each other, they correlate
 Correlation coefficient is a statistical measure of a relationship
 Reveals how closely two things vary together and thus how well wither one predicts the other
 Scatter plots show how closely related the traits are associated with
 Each point plots the value of the two variables
 Positive correlation means that two variables seem to rise or fall together
 A negative correlation could mean inverse as well as negative relationships
 Inverse means that while one variable is increasing, the other is decreasing
 A weak correlation means that there is little or no relationship- the coefficient is then zero
 Correlation indicates the possibility of a cause-effect relationship but does not prove the cause
Illusory Correlations
 A perceived non existent relationship
 Explains superstitions, beliefs.
 More likely to notice and remember the occurrence of two events in sequence
 Can be easily deceived by estimating that there is a correlation amidst random events.
Perceiving order in random events
 Random sequences often don’t look random
 Example- Flipping coins – 50% of getting each side
 Streaks may be found in any random data
 Patterns or sequences occur naturally in random data
Independent and Dependent Variables
 The Independent Variable is the value being manipulated within a given experiment
 The dependent variable is the effect produced by manipulating the independent variable.
 A variable is anything that can vary
 Random assignment is preferred so that all other variables could be equal and not favor one thing.
Statistical Reasoning
 By throwing out a big round number, one could easily mistake reality. Like when we compare percentages
and what they actually mean. An example given in the textbook is- “10% of people are lesbians or gay
men. Or is it 2 to 3% as suggested by various surveys?”
Describing Data
 One important thing while reading graphs is not to forget to read scale and figure out the range. The same
graph could look different if given different scales or a different range.
Measures of Central Tendency
 A single score that represents a whole set of scores is also known as the measure of central tendency.
 Mode is the most frequent number repeated within a given set of numbers
 Median is the midpoint
 Mean is the average of the numbers. You can find this out by adding up all the given numbers and then
dividing it by the number of numbers you have. The mean could be exaggerated or diluted based on a few
extreme scores. Like for example, the mean of 3, 4, 6 and 201 is 53.5, even though there are not many
numbers above 53.5. since the information is skewed.
Measures of Variation
 Variation describes how similar or different scores could be. When a person has low variability, we may
predict his next move, since there is not much of a chance that he will change his next move.
 The range is determined based on how far the lowest and highest scores are.
 The standard of deviation is a measure of how much numbers may deviate from one another. It shows how
much individual numbers vary from the mean. It is more informative than just the mean.
When is an observed difference reliable?
 Three principles that shall make an observed difference more reliable includes
1. Representative samples are better than biased samples
2. Less-variable observations are more reliable that those that are more variable. (consistent scores
are more reliable than those with more variation.)
3. When a study includes more cases, it is more reliable than having a study with fewer cases.
When is a difference significant?
 When there is a big difference among an average, that difference is known as the statistical significance. It
also means that this difference was not due to chance variations and that the mean is reliable.
 Statistical difference also shows the ‘likelihood’ that the result will happen by chance.
Can Libratory Experiments illuminate Everyday Life?
 The main idea is that ‘the resulting principles-not the specific findings will help everyday behaviors.’
 Douglas Mook claims that the experiment’s purpose is not re-create the exact behaviors of everyday life
but to test theoretical principles.
Does Behavior Depend on One’s Culture
 Culture is the shared ides and behaviors that one generation passes on to the next.
 It does matter since it influences our perspective on certain topics.
 Heritance does play a role though, since dyslexia can be seen more in certain races than others, the
variation of languages are influenced by our cultures and society and so does the way we live our lives,
the choices that we make.
Does Behavior vary by gender?
 Gender does play a role in behavior.
 Women are more likely to build relationships and carry on a conversation and men are more likely to
relate through advice. This information shows us a way to communicate differently with each gender. It is
a known fact that men are less likely to talk about personal feeling as much as woman, such differences,
require different approaches.
Why do Psychologists study animals?
 Human physiology resembles that of many other animals.
 Animal experiments could lead to cures/vaccines for humans
Is it ethical to experiment on animals?
 Researchers defend themselves by stating that the number of animals they use for research is only 1% of
the number of animals killed for food.
 Psychologists for the Ethical Treatment of animals want researchers to use naturalistic observation while
testing rather than libratory manipulation.
 Ethics vary from culture to culture
 Some say that the benefits out way the costs
 Scott Plous noted that each individual has a list of animals they are more concerned about.
 APA advocates minimal pain and stress placed upon animals.
Experimenting on people
 The APA states that in order to experiment on people, the following guidelines must be followed:
1. Obtain the informed consent of potential participants
2. protect them from harm and discomfort
3. treat information about individual participants confidentially
4. fully explain the research after the experiment
Value of Judgments
 Bias definitely plays a role in how an individual may interpret results and study it.
 Plays a role in which goals we would like to reach
Psychology- Dangerous?
 ‘power to deceive as well as enlighten’
 Addresses common problems, meant to enlighten.