Two basic ways to design an experiment a random

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Two Basic Ways to Design an Experiment.  a) Random Assignment, a procedure in which each participant has an equal  likelihood of being assigned to any one group within an experiment.  b) Expose all participant to all the conditions.  c) Counterbalancing, a procedure in which the order of conditions is varied so  that no condition has an overall advantage relative to the others.  5. Manipulating One Independent Variable Example: New born babies benefit from stimulation.  Researcher manipulates an independent variable: randomly assigning premature  infants either to receive three daily massage sessions for 10 days or receive  standard care and contact. 
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Chapter 2 Researcher measured several dependent variables: they found that massaged  infants had fewer health problems, more mature movement patterns, and greater  weight gain. 6. !!Manipulating Two Independent Variables Example: Sexual Arousal and Drink Alcohol (not generalizability: culturally bias)  IV. Threats to the Validity of Research 1. Internal validity: represents the degree to which an experiment supports clear causal  conditions.  2. Confounding of variables: means that two variables are intertwined in such a way that  we cannot determine which one has influenced a dependent variable.  3. Demand Characteristics: are cues that participants pick up about the hypothesis of a  study or about how they are supposed to behave.  4. Placebo Effects refers to a substance that has no pharmacological effect. People getting  a treatment show a change in behavior because of their expectations, not because the  treatment itself had any specific benefit. (Reducing Internal validity)  5. Experimenter Expectancy Effects: refers to the subtle and unintentional ways  researchers influence their participants to respond in a manner that is consistent with  the researcher’s hypothesis.  a) Double-blind procedure: is which both the participant and experimenter are kept  blind as to which experimental condition the participant is in (simultaneously  minimizes participant placebo effects and experimenter expectancy effect) 6. Replicating and generalizing the findings: External Validity: which is the degree to which the results of a study can be generalized  to other populations, settings, and conditions.  We are concerned about the external validity of the underlying principles: a) Replication is the process of repeating a study to determine whether the  original finding can be duplicated.  b) Cross cultural replication c) Goal: Increased our confidence in the generalizability of a potential causal  association between variables.   
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  • Fall '07
  • GEORGEALDER
  • Psychology, researcher, social desirability bias

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