strategic management
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EXPERİMENTAL RESEARCH
BUSN 364 – Week 12Özge Can
Stanford Marshmallow Experiment Measuring delayed gratification (ability to wait
in order to obtain something you want)
http://www.youtube.com/watch?v=x3S0xS2hdi4
A child is given a marshmallow and promised another, only if they could wait before eating the first one.
Researchers measure how long the child resists the temptation of eating it
Whether correlated with future success or not
Experimental Research
Builds on the principles of positivist perspective and natural sciences
(1) Starts with a causal hypothesis(2) Modify one specific aspect of a
situation that is closely connected to the cause, and
(3) Compare the outcome to what existed without the modification
Example Experiment
Manipulation of Independent Variable Question: Do suggestions affect memories? Method: Randomly assign participants to
groups and tell some participants that dreams indicate prior experience but do not tell that to other participants.
Results: Dream interpretations induce changes in memories of past events.
Conclusion: We can influence people’s memories by giving them erroneous information
Attributes of Experiments
Can powerfully test causal relationships An experiment is often artificial => includes
independent and dependent variables but exclude confounding variables
Confounding Variables: Factors that are not part of the intended hypothesis but have effects on variables of interest
Best for issues that have a narrow scope and sharpened focus
Attributes of Experiments
Isolates and targets one or a few causal variables; not effective for considering dozens of variables simultaneously
Best suited for micro-level (individuals, small-groups) more than macro-level (entire society) theoretical concerns
Practical and ethical limitations in social science experiments => We cannot manipulate many areas/conditions of human life
Power of Experimental Design Is it better to study these with a
survey or experiment?
Playing violent video games increases aggressive behavior
Students who sit at the front of the classroom make better grades than those that sit in the back
Power of Experimental Design Consider recent changes that have
been made on your campus (e.g., changes in graduation requirements or student life issues). Did the administration use experiments or quasi-experiments to determine whether or not to make these changes? Can you think of situations in which an experimental approach could have been used?
Parts of the Experiment
1. Treatment or independent variable (IV)2. Dependent variable (DV)3. Pretest4. Posttest5. Experimental group6. Control group7. Random assignment
Parts of the Experiment
Treatment => (stimulus, manipulation) the independent variable or a combination of independent variables in experimental research
Dependent variable => the outcome in experimental research. It is measured by paper-and-pencil tests, observation, interviews or physiological responses (e.g. heart beat, palm sweating)
Pretest => the measurement of the independent variable prior to the introduction of the treatment.
Parts of the Experiment
Posttest => the measurement of the independent variable after the treatment has been introduced into the experiment situation
Experimental group => the group that receives the treatment or in which treatment is present
Control group => the group that does not receive the treatment
Random Assignment
Participants divided into groups at the beginning of experimental research using a random process so the experimenter can treat the groups as equivalent
Randomness in statistical or mathematical sense: All participants have an equal chance of ending up in one or the other group
Increases our confidence that the groups do not differ in any systematic way
Random Assignment
How to Randomly Assign?
Controls in Experiment
By controlling confounding effects and isolating the effects of the treatment, we eliminate alternative explanations
Deception: Sometimes we intentionally mislead participants to control the experiment setting Deception involves using confederates and
cover stories (as false explanations) Using placebo: simulated or ineffectual
treatment intended to deceive the participants Blind studies: Single blind; double-blind
Steps in Experiment (1):
• Hypothesis• Choose a design• Design experiment– How to introduce IV– How to measure DV
• Locate subjects• Randomly assign subjects
Steps in Experiment (2):
• Gather pretest data• Run experiment– Introduce treatment– Measure DV– Gather posttest data– Debrief
• Analyze data
Types of Experimental Design Classical Experimental Design:
Includes random assignment, a control group and experimental group, and a pretest and posttest for each group
Pre-Experimental Design: Lack control group and random assignment Weaker than classical experiment Substitude classical experiments when they
are not possible
Types of Experimental Design Quasi-Experimental Design
We call them “quasi” (apparently, as if) becuse they are variations of the classical design
Some have control group and randomization but lack a pretest
Types of Experimental Design
Classical Experimental Design
Figure 8.6 Pretest-posttest control-group design.
Classical Experiment: Example
You have 40 newly hired waiters; you instruct them not to introduce themselves with first name and not to return during the meal to check on the customers
You randomly divide the waiters into two groups of 20 persons (random assignment) and send each group to one of two restaurants to begin working.
You record the amount of tips for all participants for one month (pretest score)
Classical Experiment: Example
Next, you retrain the group at restaurant A (experiment group) and instruct them to introduce themselves with first name and ask “Is everything fine?” 10 minutes after delivering the food (treatment).
You remind the group at restaurant B (control group) to continue as before.
Over the second month, you record the amount of tips for both groups (posttest score)
Internal Validity
Occurs when the independent variable, and nothing else, influences the dependent variable.
Anything other than independent variable threatens internal validity
Artifacts => unwanted or confounding variables that are due to the particular experimental arrangement
Threats to Internal Validity
Selection bias A bias that arise when groups in an
experiment are not equivalent with regard to the DV
HistorySomething occurs and affects the DV during
an experiment; is unplanned and outside the researcher’s control
MaturationNatural processes of growth, boredom, fatigue
that occur during the experiment and affect DV
Threats to Internal Validity
Testing: The very process of measuring, the pretest measure itself has an effect on DV
Instrumentation: Occurs when the instrument or measure of the DV changes during the experiment
Experimental mortality Participant fail to participate throughout the
entire experiment; they leave the experiment Demand characteristics
Participants “guess” the study hypothesis and respond to what they think the experimenter “demands” from them
Threats to Internal Validity
Diffusion of treatmentThe treatment “spills over” from the
experimental group and control group participants modify their behavior because they learn of the treatment
Compensatory behaviorWhen participants in the control group modify
their behavior to make up for not getting the treatment
Experimenter expectancyExperimenter indirectly makes participants
aware of the hypothesis or desired results
External Validity
The ability to generalize experiment findings
It addresses two major questions:
1. Can we generalize from the specific collection of participants in one experiment to an entire population => Population generalization
2. Can we generalize from what occurs in a highly controlled and artificial setting to most natural, “real world” situations => Naturalistic generalization
External Validity
Field Experiments
An experiment that takes place in the “field”; a natural setting instead of an artifical one (laboratory)
They have lower internal validity but higher external validity than laboratory experiments
Participants are usually unaware that they are involved in an experiment and react in a natural way Example: A confederate fakes a heart attack
on the subway to see how the bystanders react
Field Experiments
Helping behavior and gender http://www.youtube.com/watch?v=BuyIOM4
d-OA&feature=related
Practical Considerations
Planning and pilot testing We anticipate alternative explanations or
threats to internal validity during a good planning phase
Instructions to subjects Preparing instructions carefully so that all
participants understand the exact same thing Post-experiment interview
Ethically debriefing research participants the deception; understanding what participants thought and felt during the experiment
Online Resources:
This University of Denver site provides links to various online experiments in which students can participate.
http://www.du.edu/psychology/methods/
Watch it
Super Size Me Field experiment by Morgan Spurlock
(2004) http://www.youtube.com/watch?v=4Q-ez
COCVmg&feature=relmfu