Warm Up
Get your Correlation Practice sheet from the
front.
-Pick 3 of the examples and sketch out a
scatterplot that depicts the correlation
(relationship between the variables.)
1. The more control people have over their work
environments, the more productive they are.
2. The less drugs people do, the higher their grade
point average.
3. The more class days students miss, the lower their
grades are likely to be.
4. The more expensive a person's car, the fewer
successful intimate relationships they have.
5. More educated people tend not to buy designer
label clothing.
6. The more alcohol a person drinks, the lower their
scores on performance tests.
7. The fewer friends an elderly person has, the more
likely they are to have symptoms of depression.
8. The more selections from Mozart that a baby
listens to, the higher the child’s intelligence scores.
9. The more languages you speak, the higher your
scores on mathematics.
10. Correlation coefficients describe the strength of
relationships in terms of numbers. Those numbers
can be anywhere between _______ and _______.
The closer the number is to ______________, the
weaker the relationship.
11. Circle all of the legitimate correlation
coefficients:
-1.61 +0.54 +1.03 +0.01 -0.17 -0.83 -1.95 0.00
12. There was a -0.85 relationship between the
amount of exercise people do and their weight.
Explain what this means.
13._____ The more rooms a person has in their
house, the more pairs of shoes they are likely to
own.
14._____ More educated people tend not to buy
designer label clothing.
15._____ The more cigarettes someone smokes, the
more likely they are to interact with strangers.
16._____ The more friends a student has in one
class, the lower they score on tests in that class.
17._____ The fewer fruits and vegetables a person
eats, the more likely they will get cancer.
18._____ Individuals who speak more languages,
travel to more countries.
19._____ The more Beyonce your teacher listens to
before class, the more likely he is to tell jokes.
20._____ Students levels of test anxiety go down as
the time spent studying goes up
AP Psychology
Unit 1: Science of Psychology
Essential Task 1-7: Describe experimental research
design taking into account operational definitions,
independent/dependent variables, confounding
variables, control/experimental groups, random
assignment of participants, single blind/double blind
procedures, demand characteristics and applicable
biases.
Approaches
Growth
of Psych
to Psych
Careers
The Science
of Psychology
Ethics
Research
Statistics
Methods
Sampling
Descriptive
Correlation
Naturalistic
Observation
Case
Study
Survey
Experiment
Descriptive
We are
here
Central
Tendency
Variance
Inferential
Essential Task 1-7: Experimental Research
Outline
• Set up
– Independent variable
– Dependent variable
– Operational definition
• Design
– control/experimental groups
– random assignment of participants
– single blind/double blind procedures
• Possible problems
– confounding variables
– demand characteristics
– Experimenter bias
Experimental Research
• Purpose – to establish cause and effect
relationships between variables.
• Strength – You find out if one variable
(IV) causes a change in another
variable (DV)
• Weakness – Confounding variables,
experimenter bias, etc.
Outline
Independent/Dependent
Variable
Independent Variable
– Cause (what you are studying)
– This is the variable that is manipulated by the experimenter
– The variable that I change
Dependent Variable
– Effect (result of experiment)
– This is the variable that is measured by the experimenter
– It DEPENDS on the independent variable
Cause
Effect
Independent
Variable
Dependent
Variable
IV and DV in a real study
• "There will be a statistically significant
difference in graduation rates of at-risk
high-school seniors who participate in an
intensive study program as opposed to atrisk high-school seniors who do not
participate in the intensive study program."
(LaFountain & Bartos, 2002, p. 57)
• IV: Participation in intensive study program.
• DV: Graduation rates.
Outline
Help with IV vs. DV
• A good way to determine the IV from
the DV is to word the Hypothesis in the
form of an
“If ………….. then ………………” statement.
Independent
Variable
Dependent
Variable
• What follows the IF is the IV
• What follows the THEN is the DV
Outline
Create Operational Definitions
• Exact description of how to derive a
value for a variable you are measuring.
– a precise definition
– How to measure the characteristic.
• Allows for replication.
Outline
Use control and experimental groups
when you are giving treatments
• Examples of treatments:
– Drug trial
– School programs
– Food
• The experimental group will get the
treatment and the control group will
not.
Outline
Experimental Group
• In a controlled experiment, the group
subjected to a change in the
independent variable
Outline
Placebo Effect
• It's what happens when a person takes
a “medication” that he or she thinks
will help, and therefore it actually
does.
– If you gave a 7 year old decaf but told them it
was coffee they might convince themselves it
was caffeinated and therefore act hyper.
Outline
It could be both . . .
Outline
Control Group
• In a controlled experiment, this is the
group NOT subjected to a change in
the independent variable
• The control group is the group that are
given a placebo, nothing is changed
Outline
Random Assignment of
Participants
• Randomly assign participants to either
your control or experimental groups.
– Random Assignment  Experiments
– Random Selection  Surveys
Outline
Single/Double Blind Procedure
• Single Blind:
– During an experiment only the participant is
unaware of the group they are in, either the
control or experimental group
• Double Blind:
- both the participant and the researcher in
the room are unaware of the group they are
in.
Outline
Single Blind
Placebo
Drug
Outline
Double Blind
Placebo
Drug
Outline
Confounding Variables
• Variables that a researcher fails to
control for or eliminate.
• The only thing that should change is the
Independent Variable.
– If the IV is the only thing that changes, then it
must be the thing that caused the change.
• If there were confounding variables it
might have been them as well.
Outline
Demand Characteristics
Participants form an interpretation of the
experiment's purpose and unconsciously change
their behavior to fit that interpretation
Placebo
Drug
Outline
Signals the
researcher
gives off.
“Take this
drug. IT
WILL HELP
YOU!
Experimenter Bias
• Errors in a research study due to the
predisposed notions or beliefs of the
experimenter.
• Or in other words:
– the point in every research paper you’ve
ever written when you purposely ignore a
source that directly contradicts your
thesis.
Outline