PSYC 226 Ch 6, 2.17.12

PSYC 226 Ch 6, 2.17.12 - Research Strategies and Research...

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Unformatted text preview: Research Strategies and Research Strategies and Validity Validity PSYC 226 Chapter 6 Threats to Internal Validity Threats to Internal Validity Extraneous variables: Variables in the research study besides the variables of interest These are not directly investigated Part of every research study Threats to Internal Validity Threats to Internal Validity Confounding variables: Extraneous variables that influence or skew results Provides an alternative explanation for the results Example: 2 nd grade written science tes We are trying to measure science knowledge of 2 nd grade students Reading ability is a confound Threats to Internal Validity Threats to Internal Validity 3 main categories General threats for all studies Threats for between-groups studies Threats for within-groups studies Threats to Internal Validity Threats to Internal Validity General threats for all studies AKA environmental threats Things in the general environment that can affects results Examples? Threats to Internal Validity Threats to Internal Validity Environmental threats: Time of day Weather Type of room Small and dark v. bright and roomy Experimenter characteristics Threats to Internal Validity Threats to Internal Validity Threats for between-groups studies Characteristics of one group that are different from the other group(s) IQ SES Education level Etc. AKA assignment bias If 2 groups are noticeably different in some way, this could be an alternative explanation for the studys results Threats to Internal Validity Threats to Internal Validity Threats for within-groups studies: For studies testing the same people over time 5 time-related threats History Maturation Instrumentation Testing effects Regression toward the mean Threats to Internal Validity Threats to Internal Validity History: Outside events that affect participants performance differently for one treatment over other treatments Personal experiences Injury Trauma Illness Etc. Threats to Internal Validity Threats to Internal Validity Maturation: Physiological or psychological changes in participants during the study that can influence scores Relevant when working with young children or older adults in longitudinal studies How much of the change is due to treatment and how much is due to getting older? Threats to Internal Validity...
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This note was uploaded on 02/20/2012 for the course PYSC 226 taught by Professor Levens during the Spring '09 term at South Carolina.

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PSYC 226 Ch 6, 2.17.12 - Research Strategies and Research...

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