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Research Methods: Thinking Critically with Psychological Science. The Need for Psychology Science. Do Now. Fact or Falsehood Before attempting the quiz, predict how many you will get correct. Write it down, then take the quiz Complete Handouts 2-3 2-2 / 2-5.

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do now
Do Now
  • Fact or Falsehood
    • Before attempting the quiz, predict how many you will get correct.
      • Write it down, then take the quiz
    • Complete Handouts
      • 2-3
      • 2-2 / 2-5
why do we have to learn this stuff
Why do we have to learn this stuff?

Psychology is first and foremost a science.

Thus it is based in research.

Before we delve into how to do research, you should be aware of a few hurdles that tend to skew our logic.

the need for psychological science
The Need for Psychological Science

Intuition & Common Sense

Many people believe that intuition and common sense are enough to bring forth answers regarding human nature.

A bullet is fired from a gun across an open field.

A bullet is dropped from a person’s hand.

Which hits the ground first?

Intuition and common sense may help answer questions, but they are not free of error.

errors of common sense limits of intuition
Errors of Common Sense & Limits of Intuition

Try this!

Fold a piece of paper (0.1 mm thick) 100 times. How thick will it be?

800,000,000,000,000 times the distance between the sun and the earth.

Personal interviewers may rely too much on their “gut feelings” when meeting with job applicants.

did we know it all along hindsight bias
Did We Know It All Along? Hindsight Bias
  • Hindsight Bias
    • “I knew it all along”
    • “Out of sight, out of mind”
    • “Absence makes the heart grow fonder”
  • Examples:
    • Jurors told to ignore information by the judge
    • Vick is obviously a better quarterback than Kolb
    • Y2K
    • I knew the Phillies weren’t going to win the World Series last year.
    • Handout 2-2
  • Overconfidence, together with hindsight bias, can lead to overestimate our intuition
  • Do Now Quiz
  • Handout 2-3

Sometimes we think we know more than we actually know.

How many of you consider yourself above average drivers?




How long do you think it would take to unscramble these anagrams?

Try to Unscramble the following:









People said it would take about 10 seconds, yet on average they took about 3 minutes (Goranson 1978).

psychological science
Psychological Science
  • How can we differentiate between uniformed opinions and examined conclusions?
      • The science of psychology helps make these examined conclusions, which leads to our understanding of how people feel, think, and actas they do!
the scientific attitude
The Scientific Attitude
  • Three main components:
    • Curiosity (passion for exploration)
    • Skepticism(doubting and questioning competing ideas)
    • Open-Minded Humility(ability to accept responsibility when wrong).
critical thinking
Critical Thinking
  • Critical Thinking
    • “Smart thinking”
      • does not accept arguments and conclusions blindly.
    • Four elements:
      • Examines assumptions
      • Discerns hidden values
      • Evaluates evidence
      • Assesses conclusions
  • Asks:
    • What’s Your Evidence?
    • Do Your Conclusions Match Your Evidence?

The Scientific Method

A Theory isan explanation that integrates principles and organizes and predicts behavior or events.

Good theories explain by:

  • Organizing a range of observations
  • Implying hypotheses that offer testable predictions and sometimes practical applications

For example, low self-esteem contributes to depression.


The Scientific Method

  • In Psychology, a Hypothesis is not an “educated guess” or “testable question.”
  • A Hypothesis is a testable prediction, often prompted by a theory, to enable us to accept, reject or revise the theory.
    • A statement of relationship among variables.
  • Examples
      • People with low self-esteem are likely to feel more depressed.
      • Participating more in class leads to higher grades

The Scientific Method

Research Observations

Research would require us to administer tests of self-esteem and depression. Individuals who score low on a self-esteem test and high on a depression test would confirm our hypothesis.

making research scientific
Making Research Scientific
  • Must be Replicable

- Why?

  • Must be Falsifiable

- Hypothesis stated in such a way that it can be rejected (Loch Ness Monster example)

  • Must be Precise

- Use of Operational Definitions

  • Must be Prudent / Careful

- Apply simplest explanation to set of observations (i.e. falling asleep in math class)

purposes of psychological research
Purposes of Psychological Research
  • To find ways to measure and describebehavior
  • To understand why, when and how events occur
  • To apply this knowledge to solving real world problems
describing psychological research
Describing Psychological Research
  • General Terms used:
    • Variables: the events, characteristics, behaviors, or conditions that researchers measure & study
    • Subject (or participant): an individual or animal a researcher studies
    • Sample: collection of subjects researchers study (bc cannot study entire population)
    • Population: collection of people or animals from which researchers draw a sample
      • Study sample & generalize to population
operational definitions
Operational Definitions
  • Statement of procedures (operations) used to define research variables
    • Defines what the researcher will be observing and manipulating


    • Research Question – Do people with higher intelligence have greater academic achievement?
      • Variable 1 = Human intelligence defined as what an intelligence test measures (IQ Score)
      • Variable 2 = Academic achievement defined as GPA
  • Operational Definitions MUST be:
    • Measurable and Manageable
operational definitions1
Operational Definitions


– Think of a question related to psychology (behavior & mental processes) for which you want to know the answer.


What makes people happy?

Do people’s personalities change over their life?

Does involvement in athletics help academic performance?

Does excessive texting impede face-to-face interactions?

Does student consumption of caffeine in the morning improve first period grades?

  • With a partner, attempt to operationally define the following:
    • Happiness

- What factors increase happiness?

    • Aggression

- Do video games increase aggression?

    • Popularity

- What makes a person popular in HS?

    • Good Behavior

- What increases good behavior in children?


Case Study

Study 1 person (or small group) in depth

case study
Case Study



Can give incomplete or unrepresentative info

Sometimes only relies on self-report data

can be misleading

Can be subjective

Usually only 1 investigator

may lead to biased results

Cannot be used to test theories or treatments

Does NOT explain behavior

NO Cause & Effect

  • Good way to generate hypotheses
    • Can be a source of insight and ideas (Freud, Piaget, etc.)
    • Suggest further study
  • Can provide data other methods cannot
    • Rare phenomena – damage to specific brain areas
  • Provide illustrative anecdotes
    • Concrete examples of concepts & principles

Keeping up with the Kardashians or John & Kate plus 8 are case studies. Interesting, but what does it really tell us about families in general?


How long is the Amazon River?What is the population of Japan?

500 3000 2 100

Determining many people’s attitudes, opinions or behaviors (Study many people superficially)

- usually done by questioning a representative, random sample of people.

Handout 2-5 & Discuss examples

Effects of:


Range of Responses



President Obama is a good president.

Yes or No?

Estimate the % of people in class that you think agree with you

False Consensus Effect

A tendency to overestimate the extent to which others share our beliefs and behaviors.


Random Sampling

If each member of a population has an equal chance of inclusion into a sample, it is called a random sample (unbiased). If the survey sample is biased, its results are not valid.

Representative Sample


In class Sample – m/f? hair color?

Coin Flip

  • Table of Random #s
  • Potential Problems in Polls?

The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.




Relies on Self-Report Data

Can be misleading

Saying vs. Doing – behavior can’t be observed directly

Low Response Rate?

Can be Subjective

May lead to Bias

Wording? Sample?

Does NOT explain behavior

NO Cause & Effect conclusions

  • Provides a good way to generate hypotheses
  • Can provide info about many people at once
    • Cheap & relatively easy
naturalistic observation
Naturalistic Observation
  • observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

(no interference)

    • Animals in Wild
    • Self-seating patterns in lunch room
naturalistic observation1
Naturalistic Observation



Sometimes biased results

May be difficult to do unobtrusively

Does NOT explain behavior

NO Cause & Effect conclusions

Does not control for all factors that may influence behavior

  • Can be useful in generating hypotheses
  • Provides info about behavior in natural environment


– Think of a question related to psychology (behavior & mental processes) that you want to know the answer to.


What makes people happy?

Do people’s personalities change over their life?

  • Correlation Does NOT mean Causation
    • Can be used to predict
  • How is information obtained
    • Surveys
    • Quasi-experiments
    • Examples
      • GPA related to Test Scores?
      • People w/ store credit cards spend more on clothes?
  • Independent Variables that aren’t Independent (can’t be manipulated)
    • i.e. gender, age, height, weight
    • More likely to be used in correlational research
  • Correlation Coefficient
    • How well does A predict B
    • Questions to Ask:
      • Is it positive or negative? (+ / – )
        • NOT good or bad – Negative ≠ Weak
      • What is the strength? (-1.0 to +1.0)
        • 0 = no relationship
    • Scatterplot

Positive Correlation



As Variable A goes up (or down) :

Variable B also goes up (or down)

Work in same direction

# of Hours Watching TV per Day


Negative Correlation







As Variable A goes up:

Variable B goes Down

(work in opposite directions)

Years of Education

Alcoholic Drinks Per Week



Correlation Coefficient = +.62

correlation correlation and causation
CorrelationCorrelation and Causation
  • Correlation helps predict
    • Does not imply cause and effect
  • Quick Quiz Time
    • Which of the following correlation coefficients presents the strongest relationship?
      • A) .02
      • B) -.67
      • C) .55
      • D) -.14
correlation directionality
  • Correlation Coefficients
    • Do not indicate directionality, just the existence of relationship
      • A to B or B to A
  • Examples
    • Eye Movement & Reading Ability
      • Poor Readers have more erratic patterns
    • Cereal Eaters
      • Frosted Flakes – Cancer rate ½ non cereal eaters
      • Oatmeal – Cancer rate 4x non-oatmeal eaters
    • Routine Physicals in past 3 years
      • 2x as likely to report high blood pressure & cholesterol
    • TV & Childhood Obesity
      • Degree of obesity rises 2% for every hour of TV watched

What could be a 3rd variable to explain each of the following?

  • Positive Correlation between milk consumption and incidents of cancer in various society
  • Positive Correlation between body lice and good health in the New Hebrides islands
  • Positive Correlation between the quality of a state’s day care programs and the reported rate of child abuse
  • Positive Correlation between the disease pellagra and poor plumbing and sewage
    • pellagra = disease marked by dizziness, lethargy, sores & vomiting
correlation illusory correlations1
CorrelationIllusory Correlations
  • Illusory Correlation
    • Perceived non-existent correlation (random coincidence)
    • Examples
      • Partners who adopt a child get pregnant shortly after
      • “I always forget my pencil the day of a test.”
      • Sports Rituals
      • “Teachers always give HW on the same night.”
correlation perceiving order in random events
CorrelationPerceiving Order in Random Events
  • Comes from our need to make sense out of the world
    • Which is most likely sequence?
      • Coin flip Poker hand

Gambler’s Fallacy



correlation prologue quiz study time

Correlation Coefficient = +.06

CorrelationPrologue Quiz & Study Time
  • Look at the Scatter Plot
    • Does there appear to be a correlation?
    • What do you think the correlational coefficient is?
    • What does this tell us?
    • How could this be explained?
random sampling
Random Sampling
  • On a separate sheet of paper, set up the above Distribution Data Chart
  • Count the # of each color of M&Ms in your personal “intact random sample” and convert numbers to %
  • Attempt to predict the % of each color for all M&Ms (population)
  • Experiment
    • Can isolate cause and effect
    • Control of factors
      • Manipulation of the factor(s) of interest
      • Hold constant (“controlling”) factors
experimentation random assignment
ExperimentationRandom Assignment
  • Random assignment
    • Eliminates alternative explanations
      • How?
    • Different from random sample
      • How?
    • Quasi-Experiment – a study that has many of the features of an experiment but does not ensure random assignment
experimentation random assignment1
ExperimentationRandom Assignment
  • Blind (uninformed)
    • Single-Blind Procedure
    • Double-Blind Procedure
    • Which would be better? Why?
  • Placebo Effect
    • Getting treatment
    • Dr. says it will work
    • More expensive pill
experimentation random assignment2
ExperimentationRandom Assignment
  • Groups
    • Experimental Group
      • Receives the treatment (IV)
    • Control Group
      • Does not receive the treatment
    • Need for 2 Groups - comparison (Capital Punishment)
  • Within-subjects vs. Between- Subjects
    • Comparing to selves
    • Own control group (pre/post-test)
    • Which is most efficient? More resistant to individual differences?
experimentation independent and dependent variables
ExperimentationIndependent and Dependent Variables
  • Independent Variable
    • Manipulated
    • “What do researchers hope will cause the DV in the study?”
  • Dependent Variable
    • Measured
    • “What is the researcher measuring or looking for in the study?”
experimentation other concerns
Experimentation - Other Concerns
  • Confounding variable (aka Extraneous Variable)
    • Effect of random assignment on CVs?
  • Forms of Bias
    • Experimenter Bias
      • Expectations influence outcome (maze bright rats)
      • How would you control for this?
    • Research Participant Bias
      • Influenced by how they think they are supposed to behave
      • What does this relate to?
  • Validity
    • Ecological Validity (Generalizability) – Do experimental methods & results generalize to real world? (mood / creativity)
    • Internal Validity – Extent to which changes in DV are due to manipulation of IV (Is it free from bias or errors?)

If I wanted to prove that smoking causes heart issues, what are some confounding variables?

Lifestyle and family history may also effect the heart.


Experimental Design

Hypothesis: Oreo cookies improve memory

Coin Flip

Oreo Cookie

# Right on Memory Test


# Right on Memory Test

ethics in research
Ethics in Research
  • APA Guidelines for Research
  • IRB Approval
    • Internal Review Board
  • Guidelines for Humans & Animals
ethics in animal research
Ethics in Animal Research
  • Clear Purpose (Reason for using)
  • Safeguards for animal use
    • Acquire Legally
    • Treated Humanely
    • Least Amount of Suffering Possible
ethics in research1
Ethics in Research
  • Ethics in Human Research
    • Informed consent
      • Participants be told enough to enable them to choose whether they wish to participate.
      • No Coercion
    • Protect from harm and discomfort
      • No significant risk
    • Maintain confidentiality
      • Anonymity
    • Debriefing
      • Post experimental explanation of a study, including its purpose and any deceptions, to its participants.
four scales of measurement
Four Scales of Measurement
  • Nominal Data – Identifies categories
    • Ex. – yes/no answers on survey, class levels in schools
  • Ordinal Data – Identifies order in which data falls in a set
    • Ex. – any ranking of items (i.e. class rank, top ten)
  • Interval Data – Falls within a number line that has a 0 point
    • Ex. – weight, height, etc.
  • Ratio Data – Fall in a number line where 0 is just another number
    • Ex. Temperature
descriptive statistics

How can each give you a different perspective on a data set?

Is there anything misleading about the mean shown below?

Descriptive Statistics
  • Analysis of Data of an entire population.
  • Using numbers to describe a known data set.

Measures of Central Tendency

  • Mode (occurs the most)
  • Mean (arithmetic average)
  • Median (middle score)
describing data measures of variability1
Describing DataMeasures of Variability
  • Normal Curve (bell shaped)
positive negative skew
Positive / Negative Skew
  • Named for direction of the “tail”
  • Positive Skewed Distribution
  • Negatively Skewed Distribution
inferential statistics
Inferential Statistics
  • Goals
    • Make assumptions about the population at large
    • Make predictions about what might happen in the future.
      • To take what is known and make assumptions or inferences about what is not known
  • Provide a measure of how likely the results came about by chance
  • Null Hypothesis
    • The assertion that the things you were testing are not related and your results are the product of random chance events
making inferences when is an observed difference reliable
Making InferencesWhen Is an Observed Difference Reliable?
  • Representative samples are better than biased samples
  • Less-variable observations are more reliable than those that are more variable
  • More cases are better than fewer
making inferences when is a difference significant
Making InferencesWhen Is a Difference Significant?
  • Statistical significance
    • The averages are reliable
    • The differences between averages is relatively large
    • Does NOT imply the importance of the results
    • Against All Odds
hindsight bias
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 thinking1
Critical Thinking

= thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions.


= an explanation using an integrated set of principles that organizes observations and predicts behaviors or events.


= a testable prediction, often implied by a theory.

operational definition
Operational Definition

= a statement of the procedures (operations) used to define research variables.

  • i.e. Human intelligence may be operationally defined as what an intelligence test measures.

= 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 study1
Case Study

= an observation technique in which one person is studied in depth in the hope of revealing universal principles.


= a technique for ascertaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.


= 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
Random Sample

= a sample that fairly represents a population because each member has an equal chance of inclusion.

naturalistic observation2
Naturalistic Observation

= observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.


= a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

correlation coefficient
Correlation Coefficient

= a statistical index of the relationship between two things (from -1 to +1).


= a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation).

illusory correlation
Illusory Correlation

= the perception of a relationship where none exists.


= a research method in which an investigator manipulates one 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 assigment
Random Assigment

= assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between those assigned to the different groups.

double blind procedure
Double-Blind Procedure

= an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or the placebo. Commonly used in drug-evaluation studies.

placebo effect
Placebo Effect

= experimental results caused by expectation alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.

experimental group
Experimental Group

= in an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

control group
Control Group

= in an experiment, the group that is NOT exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of treatment.

independent variable
Independent Variable

= the experimental factor that is manipulated; the variable whose effect is being studied.

confounding variable
Confounding Variable

= a factor other than the independent variable that might produce an effect in an experiment.

dependent variable
Dependent Variable

= the outcome factor; the variable that may change in response to manipulations of the independent variable.


= the most frequently occurring score(s) in a distribution.


= the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.


= the middle score in a distribution, half the scores are above it and half are below it.


= the difference between the highest and lowest score in a distribution.

standard deviation
Standard Deviation

= a computed measure of how much scores vary around the mean score.

normal curve
Normal Curve

= a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scored fall near the mean (68 percent fall within one standard deviation of it) and fewer and fewer near the extremes.

statistical significance
Statistical Significance

= a statistical statement of how likely it is that an obtained result occurred by chance.


= the enduring behavior, ideas, attitudes, and traditions shared by a group of people and transmitted from one generation to the next.

informed consent
Informed Consent

= an ethical principle that research participants be told enough to enable them to choose whether they wish to participate.


= the postexperimental explanation of a study, including its purpose and any deceptions, to its participants.