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Ch 9: Intro to T Statistic: A T Distribution is the complete set of T…
Ch 9: Intro to T Statistic: A T Distribution is the complete set of T values computed for every possible sample for a specific sample size n or a specific degrees of freedom df. The t distribution approximates the shape of a normal curve
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T Statistic used to test hypothesis about an unknown population mean µ when the value of is unknown. Formula is same structure as Z score, but uses estimated standard error in denominator
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Shape of t Distributions
Are: Bell shaped, symmetrical, have mean of 0
BUT more variability, especially when sample size is small. AND tend to be flatter and more spread out
BECAUSE the bottom of the z formula doesn't vary and the bottom of the t statistic does. The sample variance changes from one point to the next, so the estimated standard of error varries too
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Reminder: Sample size does affect hypothesis test, does not affect measures of effect size (Cohen's D
Reminder: Sample variance does influence hypnosis test, does influence measures of effect size. High variance reduces likelihood of rejecting null hypotenuse
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