Lecture_5 T &acirc;€“ Tests

# Lecture_5 T &amp;acirc;€“ Tests - Lecture4 TTests...

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Lecture 4 T – Tests Tuesday February 16 th 10:10 – 11:00am Change is the watchword of progression. When      We tire of well-worn ways, we seek for new. This restless craving in the souls of men      Spurs them to climb, and seek the mountain view. - Ella Wheeler Wilcox

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Today’s Outline One Sample T-Tests One Sided Hypotheses Two Sided Hypotheses Two Sample T-Tests One Sided Hypotheses Two Sided Hypotheses What about SAS 9.2?
Quick Notes for Local Paths When accessing local paths while using SAS remotely (computer labs), You CAN use local drives by using the keyword: \\tsclient libname stat200 "\\tsclient\I\Stat480\HW4\" ; (This would allow you to use a USB key to hold everything.) Local Drive Letter

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One-Sample T-Tests
Specify the Hypotheses Does the average student exercise more than 3 hours per week? H 0 H A Null Hypothesis Alternative Hypothesis What we want to Disprove What we want to Prove

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> Specify the Hypotheses Does the average student exercise more than 3 hours per week? H 0 H A µ Hours of Exercise µ Hours of Exercise 3 ? ?
One Sample Test How do we translate the hypotheses into SAS code? Proc ttest data =stat200.complete; var HrsExer; run ; SAS will only perform a two-sided test.

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One Sample Test Don’t forget to specify the null value, if it’s different from 0.0. Proc ttest data =stat200.complete H0 = 3.0 ; var HrsExer; run ;
One-Sample T-Test Output The TTEST Pr ocedur e Var i abl e: Hr sExer N Mean St d Dev St d Er r M i ni mum Maxi mum 997 5. 1404 3. 9225 0. 1242 0 20. 0000 95% CL Mean St d Dev CL St d Dev 4. 8966 5. 3842 3. 7576 4. 1027 DF t Val ue Pr > | t | 996 17. 23 <. 0001

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Convert from 2-sided to 1-sided Is mean on same side as alternative hypothesis? If so , then p-value = ( 2-sided p-value ) / 2.0 If not , then p-value = 1.0 – ( 2-sided p-value ) / 2.0
Convert from 2-sided to 1-sided 1. Is mean on same side as alternative hypothesis?

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## Lecture_5 T &amp;acirc;€“ Tests - Lecture4 TTests...

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