1. Hypothesis tests Single sample Z
( ) – (μ)
_________________
Zobs=

2. Hypothesis tests Single sample t
( ) – (μ)
__________________
tobs= SX

3. Hypothesis tests Two samples?
( ? ) – (?)
_________
(?)
tobs=
? = Depends on type of two-sample (t) test
Related scores (dependent)
Unrelated scores (independent)

4. Two Sample Tests When do use dependent t test?
When scores are related
Same person is on both conditions
Pre-post design
When participation in on condition does not affect performance in other condition
When scores are matched on meaningful variable
Steroids and weightlifters
GPA and SAT scores

5. Two Sample Tests Advantages of dependent t test
Matched scores have less error/variability
Unrelated
(Observed Value) – (Expected value under H0)
__________________________________________
Standard error of H0 distribution (Large)
Related
(Observed Value) – (Expected value under H0)
__________________________________________
Standard error of H0 distribution (Small)

6. Two Sample Tests Obstacles to using dependent t test
If impossible to participate in both conditions
Normal vs. Parkinsons
Men vs. Women
If participation in one condition affects other conditions
Conjunction fallacy
Solving a reasoning problem
If unequal number of participation in two conditions

7. Two Sample T-test Dependent Means
Compute difference scores for all PAIRS of subjects
And then use the ordinary one-sample t test
D = Difference score = X2 – X1
Degrees of freedom = (Number of Pairs)-1

15. Outline of hypothesis evaluation
Dependent T-test
Outline of hypothesis evaluation
I. State null and alternative hypotheses
H0 : Dobs = 0
H1 : Dobs = 0
II. Collect a sample and compute the observed values of the sample statistic and the test statistic
III. Set the criterion for rejecting H
IV. Interpret the results

16. Dependent T-test

17. Dependent T-test

18. Dependent T-test

19. Dependent T-test