PSYC 2021 Lecture Notes - Lecture 8: Null Hypothesis, Alternative Hypothesis, Test Statistic
3 Apr 2017
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Document Summary
Specifies the difference between m and due to chance. Obtained difference between data and / expected difference due to chance. For normally distributed z-scores, use the unit normal table to determine critical z required to reject. To use z, population variance ( 2) must"ve known to calculate standard error ( qm) More often than not, 2 is unknown. Solution use sample variance (s2) to estimate 2) To test hypothesis when is unknown use t- test. Determine critical value of t using the t distribution table. df and t- distribution. Degrees of freedom ( ---> the number of scores in a sample that are free to vary. Unlike the z-distribution (always normally distributed) the shape of the t- distribution varies as a function of df. Use degree of freedom and alpha level to find the value of t. Null hypothesis ---> the treatment has no effect. Alternative hypothesis ---> the treatment has an effect.
