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EXAM 2

Terms in this set (12)

When Should Dependent T-Test be Used?
-Scores in two conditions are meaningfully realted
—> One group being tested with the manipulation of the IV for the same group
-Within subject experimental design
-Non-experimental pretest/posttest
-Match-subject designs:
—> Naturally occuring pairs
—> Experimentally matched pairs
What Are the Assumptions of the Dependent Samples T-Test:
Which Assumption is MOST CRITICAL?
1) The difference scores (i.e., each pair of numbers) are independent from one another******
2) The scores for both conditions are drawn from normal population
What is the Null Hypothesis for a Dependent T-Test?
H0= MU(1) = MU(2)
- The two conditions have the same score
What is the Alternative Hypothesis for a Dependent T-Test?
H1= MU(1) =/ MU (2) (DOES NOT EQUAL EACH OTHER)
-The two conditions lead to different scores
How do we Measure Effect Size for Dependent T-Tests? How Does Effect Size Differ from Statistical Significance?:
Cohen's d= (|MD|)/(SD)= effect size
Interpretation: small (.2) < .5-.75 < large (.08)

-Statistical significance is the probability that the observed difference between two groups is due to chance, effect size is independent of sample size. Statistical significance depends on both sample size and effect size.
—> Mean Difference/ (og) Sample SD
Report SPSS Results APA Style: Dependent T-Test
A dependent-samples t-test indicates that __________ (M= _.__, SD= _.__) were the same/different than ________ (M= _.__, SD= _.__), t(dF)= _(t)_, p ____, d=__.

(ALL TWO DECIMAL PLACES)
When Should We Use Independent Samples T-Test?
-Data is collected from two separate, unrelated samples
-Basic two-group design
-Two group protest/posttest design
-Two group quasi-experimental design
What Are the Assumptions of Independent Sample T-Test?
1) The observations are independent from one another*****
2) Homogeneity of variance: both populations have the same variance
3) Both samples are drawn from normal populations
What is the Null Hypothesis for an Independent Sample T-Test:
H0= MU (1) = MU (2) OR MU(1)- MU (2) =0

THE TWO CONDITIONS LEAD TO THE SAME SCORE
What is the Alternative Hypothesis for an Independent Sample T-Test:
H1= MU (1) /= MU (2) or MU(1)- MU (2) /= 0

THE TWO GROUPS HAVE DIFFERENT SCORES
How do we Measure Effect Size for Independent Samples T-Test?
-Statistically significant difference /= substantial difference
-Cohen's d= mean difference/ standard deviation (pooled estimate)
—> |M1-M2|/ SQRT [(S1+S2)/2] IF SAMPLE SIZE IS EQUAL
—> |M1-M2|/ SQRT [(SS1+SS2)/(df 1 + df 2)] IF SAMPLE SIZE IS UNEQUAL
Report SPSS Results APA Format: Independent Sample T-Tests:
An independent sample t-test indicated that ___________ (M= _.__, SD= _.__) was the same/different as ________ (M= _.__, SD= _.__), t(df) = p____, ____.
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