Pass in PsycInfo assignment 1

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Pass in PsycInfo assignment 1

• review WWW assignment 2 due next week
• assign partners next week
• practice identifying independent/dependent
  variables
• practice identifying extraneous variables/
  confounds
• Assignment 3 Variables

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IV/DV/Extraneous/Confound

• Independent Variable variables controlled by the
  experimenter in an attempt to test the effects on
  some outcome, the dependent variable
• -variable that is manipulated by the
  experimenter. It is determined by the
  experimenter not the participant
• Quasi-independent existing quality, levels not
  assigned at random (ie. Age)
• Dependent Variable variable measured in a
  study. It is determined by the subject.
• -The outcome variable of research
• -dependent variable observed for effects due to
  the influence of another factor , the IV

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IVs and DVs

• Independent Variable
• the variable which is manipulated by the
  experimenter
• under the control of exp. (ie,. Independent of
  participants behaviour)
• The set values or conditions of the IV are called
  the levels
• ie. Interested in sleep deprivation and motor
  skills
• decide to have 3 levels
• 12 hours without sleep
• 24 hours
• 36 hours

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IV/ DV Example 1

• ie. Interested in sleep deprivation and motor
  skills
• decide to have 3 levels
• 12 hours without sleep
• 24 hours
• 36 hours
• Then you measure participants on a hand/eye
  coordination task
• DV score on coordination task

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Identify IV (levels) and DVExample 2

• Youre interested in conducting a true
  experimental study to determine whether people
  are more satisfied after they succeed at an easy
  or a difficult task
• IV task difficulty
• levels 2 easy/hard
• DV satisfaction

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EXAMPLE 3

• A Researcher conducts an experiment to
  determine the effect of a new drug on the
  incidence of epileptic seizures. 40 epileptics
  are selected from the 150 epileptics being
  treated at a local hospital. 20 receive the new
  drug and 20 are given their traditional
  medication. The number of seizures in each of
  the participants is recorded for one month.
• IV
• type of medication
• Levels of IV?
• 2
• new drug, traditional drug
• DV
• number of seizures

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IV manipulated by experimenterDV what is
measured and recorded

• A Researcher conducts an experiment to
  determine the effect of a new drug on the
  incidence of epileptic seizures. 40 epileptics
  are selected from the 150 epileptics being
  treated at a local hospital. 20 receive the new
  drug and 20 are given their traditional
  medication. The number of seizures in each of
  the participants is recorded for one month

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Example 4

• A researcher is interested in testing the
  effectiveness of type of reading program on
  childrens reading skills. Children are assigned
  to either a tutoring, tutoring and rewards, or
  no tutoring and no rewards group. Reading scores
  are recorded after two weeks time.
• IV type of reading program
• 3 Levels
• tutoring
• tutoring and rewards
• no tutoring and no reward
• DV reading score

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IV/DV- Example 5

• Would you take a drink of water from a
  fountain if someone were sitting right next to
  it? In an experiment investigating participants
  willingness to violate personal space, Barefoot,
  Hoople and McClay (1972) positioned a male or
  female experimenter near a water fountain. The
  experimenter was positioned either one foot (near
  condition), five feet (far condition) to the
  right of the fountain, or across from the
  fountain, ten feet away (control condition). The
  number of people passing the fountain was
  recorded along with how long a person spent at
  the fountain if he or she chose to drink. The
  results showed that fewer participants drank from
  the fountain in the near condition than in the
  far or control conditions.
• IV 1) distance the experimenter sat from the
  water fountain
• levels (one foot, five feet, or 10 feet)
• 2) sex of experimenter 2 levels (male or
  female)
• DV 1) number of people who stopped to drink
• 2) amount of time spent at the fountain

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Extraneous Variables / ConfoundsUnjustified
Conclusions

• Extraneous Variables any factors other than
  the independent or quasi-independent variables
  youre considering that might affect scores on
  the dependent variable. (ie, age, noise)
• Confounds A confound or a confounding variable
  is an extraneous variable which varies
  systematically with your independent variable. It
  provides an alternative explanation for your
  results over and above your manipulation of the
  IV. (ie. A difference between conditions or
  groups other than what was intended).
• Other problems poor measurement of constructs,
  unjustified causal inferences

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Uncontrolled VariablesExample 1

• An experimenter wanted to test the effects
  of music on learning by fourth grade children.
  To keep his work at a manageable level, he
  decided to introduce music into the classroom
  every afternoon for one week. No music would be
  played during the morning hours. The
  experimenter chose the music carefully, the music
  was from familiar tv cartoons, and the loudness
  was moderate. After the week of music
  presentation, the students were given tests on
  the morning and afternoon material. Test scores
  for the morning material were much higher than
  the scores on the afternoon material. Thus, the
  experimenter concluded that cartoon music
  disrupted learning in the classroom.
• Is the conclusion justified? Why or why not?
• No,
• Confound present music played only in
  afternoon. Time of day may account for higher
  test scores

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Uncontrolled VariablesUnjustified
ConclusionsMore examples

• Data Fifty percent of women who take birth
  control pills have occasional hot flashes. Men
  almost never have hot flashes.
• Conclusion Birth control pills cause hot
  flashes
• Conclusion justified?
• No. Why not?
• Correlation doesnt prove causation. Hot flashes
  may occur in women even if they dont take birth
  control pills.

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Uncontrolled Variables -Example 2

• An experiment was designed to evaluate the
  effect of subliminal perception on thirst. The
  participants (university students) were randomly
  assigned to two groups. One group watched a
  movie (Return of the Pink Panther) that did not
  contain subliminal messages. The other group
  watched a movie (The Desert Fox) in which the
  message Have a cool drink! was repeatedly
  flashed on the screen so quickly that it was not
  consciously noticeable. Because of time
  limitations, the first group watched the movie at
  830am, the second at 1130am. The dependent
  measure was the amount of ice water consumed by
  the participants as they watched the movie. The
  second group drank significantly more ice water
  than the first therefore, the researchers
  concluded that subliminal messages can affect
  thirst.

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Uncontrolled Variables -Example 2

• Agree with their conclusion?
• No. Why not? Whats the problem?
• -2 confounds present
• time of day people may be thirstier at 830 than
  1130
• movie used Desert Fox Has a dry connotation
  as opposed to Pink Panther , amount of water
  drank may be due to the movie not the subliminal
  message.

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Another Example

• A researcher wants to examine the relation
  between personality and health habits. The
  researcher believes that people who have low
  self-esteem will be more likely to have unhealthy
  habits (e.g. smoking, overeating, poor dental
  hygiene). To conduct the research, the
  researcher distributes two questionnaires to all
  students currently enrolled in Introductory
  Psychology courses. The first questionnaire is a
  personality inventory that measures self-esteem.
  The second questionnaire is a survey of the
  persons health habits. The researcher examines
  the data and concludes that self-esteem and
  unhealthy habits are related in this sample
  those with lower self-esteem tend to engage in
  more risky personal health behaviours than those
  with higher self-esteem.

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• Any problems with this conclusion?
• Unjustified, why?
• Number of other factors left unexamined
  (extraneous variables) which could account for
  both low self-esteem and personal health
  behaviours
• background
• income
• many plausible answers
• another extraneous variable intro psyc students
  may differ in some manner than general population
  (external validity)

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Uncontrolled VariablesExample

• An employee at a certain cafeteria wanted to
  show his boss that the policy of serving exotic
  juices with breakfast (if the customer requested
  it) was a wasteful practice. He thought people
  just bought the exotic juices to impress their
  friends and that they did not really like the
  taste of the juices. In order to gather
  evidence, the man recorded the flavour of the
  juice contained in the glasses of those patrons
  who failed to drink all of their juice. At the
  end of the morning he had counted a total of
  fifty less than completely finished glasses of
  juice. Of these, forty were of the exotic
  variety and only ten were of the non-exotic
  variety (orange juice). Because 80 were of the
  unfinished juices were of the exotic variety, the
  employee concluded that his evidence was sure to
  convince his boss. Do you agree?
• No Why not?
• Unjustified conclusion wrong adjustment made,
  need to adjust for s of each type of juice
  ordered, perhaps 200 people ordered exotic juices
  and 40 left unfinished, compared to 50 nonexotic
  and 10 left unfinished

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Practice!

• Assignment 3- Variables assignment
• Due in 2 weeks time
• Oct 12 (A) Oct 14 (B/C)