PSYC 310 Chapter Notes - Chapter 9: Design Of Experiments, Wilcoxon Signed-Rank Test, Internal Validity
19 Sep 2018
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Every participant is subjected to every treatment (including control). Still need to be careful of selection bias, however; no threat of assignment bias. Every participant experiences every level of the iv. You measure multiple scores per participant, and each participant serves as their own comparison. All participants are treated the same way , there are not independent groups. All participants saw all three categories of words (all levels of the iv) Multiple scores per participant (for each of the three categories, how many words were accurately recalled?) Accounts for individual variation in memory abilities. Characteristics of the environment may change from one treatment condition to the other. Temperature and weather change, amount of daylight. History, maturation, regression to the mean, attrition . Order effects can produce changes in the scores (not caused by the treatments) from one treatment condition to another. Changing the order in which the treatment conditions are applied from one participant to another to prevent order effects.
