Lecture Slides PSY201 10.7.13

Determine the signicance cuto use the t table 4

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Unformatted text preview: ing amounts of informa>on.   When there are infinite degrees of freedom, the t distribu>on is the same as the normal curve. ▪  This is because your sample is infinitely large and thus, becomes the same as the popula>on… so the es>mate is perfect 7 10/6/13   To find cutoffs on the t distribu>on, you use a t table.   Step 3 of hypothesis tes>ng involves determining the cutoff sample score for rejec>ng the null hypothesis   Previously, we looked for the cri>cal Z score using the normal curve table   For a t test, we use the t table to determine the cutoff sample score   Step 4 involves finding your sample mean’s score on the comparison distribu>on   Conver>ng the raw mean to a t score Steps in Hypothesis Tes4ng Difference from when Popula4on Variance is Known 1. Restate the ques>on as a research hypothesis and a null hypothesis about the popula>ons. No difference in method 2. Determine the characteris>cs of the comparison distribu>on •  Popula>on mean •  Popula>on variance •  Standard devia>on of the distribu>on of sample means •  Shape of the comparison distribu>on •  No difference in method •  Es>mate pop variance from the sample •  No difference in method, but based on es>mate from sample •  Use the t distribu>on with df = N  ­ 1 3. Determine the significance cutoff Use the t table 4. Determine your sample’s score on the comparison distribu>on. No difference in method (but called a t score) 5. Decide whether to reject the null hypothesis. No difference in method 8 10/6/13 1.  Restate the ques>on as a research hypothesis and null hypothesis about the popula>ons. 2.  Determine the characteris>cs of the comparison distr...
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