A look at psychological research

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A look at psychological research
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General principles

• The specious attraction of anecdotes
• The concern for precise measurement
• Operational definitions definitions which
  specify the procedure used to measure something
• Also, a way to give a studys focus of concern a
  numerical value
• How do you measure anger, love, intelligence?

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Population samples

• Population the entire
• group of individuals of
• interest
• Sample a small group
• chosen from the popu-
• lation

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Types of samples

• Convenience a sample chosen because of its
  availability
• Far from ideal, but very common
• The study of 20 year old college sophomores. ?
• Representative a sample which closely mirrors
  the population in all characteristics likely to
  affect the results
• Ideal but hard to find

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Samples cont.

• Random samples a sample in which every
  individual in the population has an equal chance
  of being selected.
• Hard to get, but many benefits
• Cross-cultural samples samples which include
  groups from at least two separate cultures
• Discuss concerns in Interpretations

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Research designs

• Naturalistic observations
• A careful examination of
• an individuals or animals
• behavior in more or less
• natural conditions
• No manipulation, just observation
• Often the first step in generating hypothesis

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Case histories

• A thorough description of a
• person or small group of
• people with unusual or
• noteworthy qualities
• Another source of hypothesis
• Just a super-sized anecdote?

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surveys

• A study of the prevalence of certain beliefs,
  behaviors, or attitudes based upon peoples
  responses to specific questions
• Many problems
• sampling
• nonchalance
• the questions
• bias

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correlations

• A measure of the relationship between two
  variables
• Variable a measurable item that can vary in
  magnitude
• Correlational study a procedure in which the
  investigator measures the relationship between
  two variables without controlling either one

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Correlationsexamples

• Between class attendance and final grade
• Between hours worked and earned
• Between smiles given and smiles received
• Between miles run/week and 5k time
• Between hours on internet and final grade
• Between exercise sessions and weight
• Between hair color and grade point average

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Correlations graphicexamples
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The correlation coefficient

• R the mathematical relationship between two
  variables, ranging from -1 to 1
• Positive correlations approach 1
• Negative correlations approach -1
• A R of 0 means that there is no relationship
  between the two variables
• Look to Rs absolute value when assessing its
  strength

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Illusory correlations

• An apparent relationship based upon casual
  observations of unrelated or weakly related
  events
• Do people really get
• wild under a full moon?
• Does the weather affect
• arthritis symptoms?

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Correlations and causation

• No matter how it might seem, correlations do not
  tell us about cause and effect
• We never really know if changes in one variable
  affects the other, or
• If a third, lurking, variable controls them both.
• Correlations help us predict but not explain or
  control behavior or experience.

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experiments
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experiments

• A study in which the investigator manipulates at
  least one variable while measuring at least one
  other variable
• By adjusting one variable or factor, while
  keeping all other factors constant, we can
  determine if that factor causes changes in the
  other(s)

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More definitionsvariables

• Independent variable the variable which is
  manipulated, or adjusted, by the investigator
• Dependent variable the variable which is
  measured by the investigator to determine the
  effects of the independent variable
• Thoughtfully quantified through the operational
  definition

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Even moregroups

• Experimental group receives the treatment
  (independent variable) that the experiment was
  designed to test
• Control group handled exactly the same as the
  experimental group except for the independent
  variable
• Control groups usually receive a placebo

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Hazards to be prepared for

• Biased groups
• to make sure that the experimental and control
  groups are as similar as possible, before being
  introduced to the independent variable we use
  random assignment
• every participant must have an equal chance of
  being placed in either the experimental or the
  control group

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more hazards

• Even unconsciously, investigators want to see
  their hypothesis confirmed and unintentionally
  might distort the results
• Also, the experiments participants might try to
  help prove the hypothesis
• Solution Double blind a procedure in which
  both the observer and the participant are unaware
  of which participants received which treatment
  and the experiments goals

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review

• Hypothesis
• Select Method Operational Definition
• Acquire Sample
• Random Assignment of groups
• Run experiment (double blind)
• Collect and analyze results (data)