Psyc_315_-_Winter_2010_-_Class_14

Psyc_315_-_Winter_2010_-_Class_14 - Introduction to...

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Introduction to Hypothesis testing and 1-tailed vs. 2-tailed tests Chapter 17 2 Scientific Method Observe natural phenomena Formulate Hypothesis Test hypothesis via rigorous experiment Modify Hypothesis Establish theory based on repeated validation of results 3 Inferential Statistics • Involves making inferences about populations based on information in samples (as compared to descriptive statistics, which merely summarize known data). • Used to draw conclusions about the world in general (i.e., population) based on results obtained from a particular experiment or study (i.e., sample). 2 main purposes of inferential statistics hypothesis Testing Parameter Estimation
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4 Hypothesis Testing Hypothesis Testing : • A systematic procedure for deciding whether the results of a research study, which examines a particular subgroup of the population, supports a particular theory which applies to the population. Hypothesis Experiment Results Accept or Reject the Hypothesis Hypothesis Testing Inferential Statistics 5 Core Logic Of Hypothesis Testing • We are testing the notion that the experimental manipulation makes no difference…. why? • If the notion of no difference can be rejected, this supports the idea that the experimental manipulation does make a difference. 6 Core Logic Of Hypothesis Testing • Null Hypothesis (H 0 ): – Assumed to be true and formally tested (innocent until proven guilty). – Opposite to the research hypothesis. – Usually assumes that manipulation causes no change (null event). – Determines the sampling distribution to be used (usually 95%) – Hypothesis about which decision to “reject” or “retain” is made.
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7 Core Logic Of Hypothesis Testing • Research Hypothesis (H 1 ): – Alternative population condition that is “supported” or “asserted”. – Rejection of H0. – Usually reflects the underlying research question of the researcher. 8 Example: Alcohol and Pregnancy On the label of a wine bottle … “According to the surgeon general, women should not drink alcoholic beverages during pregnancy …” • Reason for the warning: Maternal alcohol consumption may result in birth defects such as …
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This note was uploaded on 04/29/2010 for the course PSYCH 315 taught by Professor Afroditipanagopoulos during the Winter '10 term at Concordia Canada.

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Psyc_315_-_Winter_2010_-_Class_14 - Introduction to...

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