# 12_dep_t - differences X S X t-= Dependent t Example...

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Dependent  t -test

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Varieties of  t 1-Sample (only one kind) 2-Sample (two kinds) Independent samples – groups are unrelated Experimental vs. control groups (at random) Male vs. female participants (unrelated) Dependent samples – groups are related Same person in both groups Left hand vs. right hand Pain-free vs. placebo Groups are related somehow Wife, husband Cancer patient, friend
Dependent  Formulas D D S D t μ - = Observations come in pairs. Brother, sister, repeated measure. Problem solved by finding diffs between pairs D i =X i1 -X i2 . 1 ) ( 2 2 - - = N D D s i D N s est D MD = σ . N D D i = ) ( MD est D t . ) ( 2 1 - - = df=N(pairs)-1 Dependent t is equivalent to a single sample t computed on

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Unformatted text preview: differences . X S X t-= Dependent t Example Brother (X 1 ) Sister(X 2 ) 5 7 7 8 3 3 5 = X 6 = X Diff 2 1 1 1 1 = D 58 . 3 / 1 . = = MD est σ 72 . 1 58 . 1 . ) ( = =-= MD est D E D t 1 1 ) ( 2 =--= ∑ N D D s D 2 ) ( D D-N s est D MD = . Six Steps 1. Alpha = .05 2. Null & Alt: 3. Calc stat: 4. Crit value: df = N-1 =2, alpha .05, 2 tails. 5. Decision rule: 6. Conclusion: 2 1 : μ μ= H 2 1 : μ≠ a H 72 . 1 58 . 1 . ) ( 2 1 =-=--= MD est D t σ Reject if |t obt | > t crit N.S., i.e., no difference. t = 4.30...
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## This note was uploaded on 05/21/2011 for the course PSY 3204 taught by Professor Brannick during the Spring '10 term at University of South Florida.

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12_dep_t - differences X S X t-= Dependent t Example...

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