The Experiment

1
The Experiment

• Only research method capable of showing cause and
  effect

2
Experimental Research

• Explores cause and effect relationships.

Aggressive behavior
Eating too many bananas causes
3
Steps in Designing an Experiment

1. Question
2. State Hypothesis
3. Pick Population Random Selection then Random
   Assignment.
4. Operationalize the Variables
5. Identify Independent and Dependent Variables.
6. Look for Extraneous Variables
7. Type of Experiment Blind, Double Blind etc..
8. Gather Data
9. Analyze Results

4
Hypothesis

• A statement about the relationship between two or
  more variables
• Must be testable and refutable
• Instead of proving the hypothesis, science
  usually tries to disprove a null hypothesis.
• Null Hypothesis (H0)
• opposite of hypothesis

Hypothesis Example H1 Gender has an effect on
spatial ability H0 Gender does not have an
effect on spatial ability
5
Population The larger group of people from
which a sample is drawn

• Sample Representative of the population
• Two ways to get sample
• Random Every member of the pop has chance
• Stratified Sample is put together by picking a
  
• group statistically equal to the
  population

6
Random Assignment

• Assigning participants to experimental and
  control conditions by random assignment minimizes
  pre-existing differences between the two groups.

7
Variables

• Independent Variable (I.V.) manipulated by
  experimenter
• Dependent Variable (D.V.) MEASURED variable
  influenced by independent
• Operational definition
• Confounding/extraneous variables

8
Independent Variable

• An Independent Variable is a factor manipulated
  by the experimenter. The effect of the
  independent variable is the focus of the study.
• For example, when examining the effects of breast
  feeding upon intelligence, breast feeding is the
  independent variable.

9
Dependent Variable

• A Dependent Variable is a factor that may change
  in response to an independent variable. In
  psychology, it is usually a behavior or a mental
  process.
• For example, in our study on the effect of breast
  feeding upon intelligence, intelligence is the
  dependent variable.

10
Control Measures

• Single-Blind subject unaware of assignment
• Double-Blind subject and experimenter unaware of
  placement

11
Experimental Vocabulary

• Independent Variable factor that is manipulated
• Dependent Variable factor that is measured
• Extraneous Variables factors that effect DV,
  that are not IV.
• Experimental Group Group exposed to IV
• Control Group Group not exposed to IV
• Placebo inert substance that is in place of IV
  in Control Group

12
Analyze Results

• Use measures of central tendency (mean, median
  and mode).
• Use measures of variation (range and standard
  deviation).

13
Experimentation
A summary of steps during experimentation.
14
Flaws in Research

• Sampling Bias
• Overgeneralization
• Placebo effect
• Hawthorne/Barnum effect
• Demand Characteristics
• Experimenter Bias

15
APA Ethical Guidelines for Human Research

• All research goes before an institution review
  board (IRB) for approval
• Research involving humans must meet the following
  standards
• 1. Informed Consent-participants must know that
  they are involved in research and give their
  consent or permission
• 2. Deception-if the participants are deceived in
  any way about the nature of the study the
  participants must be debriefed after the study is
  over
• 3. Coercion-participants cannot be coerced in any
  way to participate in the study.
• 4. Anonymity/Confidentiality -the identities and
  actions of participants must not be revealed in
  anyway by the researcher.
• 5. Risk -participants cannot be placed at
  significant mental or physical risk. DO NO HARM
• 6. Debriefing Procedures-participants must be
  told of the purpose of the study and provided
  with ways to contact the researchers about the
  results after the study is complete
•  

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Ethics in Research with Animals

• 1. (Purpose) They must have a clear scientific
  purpose. The research
• must answer a specific, important scientific
  question. Animals are chosen because they are
  best-suited to answer the question at hand.
• 2. (Care) They must care for and house animals in
  a humane way.
• 3. (Acquiring animals) They must acquire animal
  subjects legally.
• Animals must be purchased from accredited
  companies. If wild
• Animals must be used, they need to be trapped in
  a humane way.
• 4. (Suffering aka DO NO HARM) They must design
  experimental procedures that employ the least
  amount of suffering feasible.
• 5. (Supervision) A trained psychologist must
  supervise all research with
• animals