In: Statistics and Probability
An educational psychologist has developed a meditation technique to reduce anxiety. The psychologist selected a sample of high anxiety students that are asked to do the meditation at two therapy sessions a week apart. The participants' anxiety is measured the week before the first session and at each subsequent session. Below are the anxiety scores for the participants. What can the psychologist conclude with an α of 0.01?
before | session 1 | session 2 |
9 6 8 5 8 6 9 6 8 |
7 7 6 7 9 9 7 7 7 |
6 5 5 4 5 6 5 5 4 |
a) What is the appropriate test statistic?
---Select--- na one-way ANOVA within-subjects ANOVA two-way
ANOVA
b) Obtain/compute the appropriate values to make a
decision about H0.
critical value = ; test statistic =
Decision: ---Select--- Reject H0 Fail to reject H0
c) Compute the corresponding effect size(s) and
indicate magnitude(s).
η2 = ; ---Select--- na trivial
effect small effect medium effect large effect
d) Make an interpretation based on the
results.
At least one of the sessions differ on anxiety.None of the sessions differ on anxiety.
e) Regardless of the H0
decision in b), conduct Tukey's post hoc test for
the following comparisons:
1 vs. 2: difference = ;
significant: ---Select--- Yes No
1 vs. 3: difference = ;
significant: ---Select--- Yes No
f) Regardless of the H0
decision in b), conduct Scheffe's post hoc test
for the following comparisons:
1 vs. 3: test statistic = ;
significant: ---Select--- Yes No
2 vs. 3: test statistic = ;
significant: ---Select--- Yes No
a)
one-way ANOVA
b)
count, ni = | 9 | 9 | 9 | |||
mean , x̅ i = | 7.222 | 7.33 | 5.00 | |||
std. dev., si = | 1.481 | 1.000 | 0.707 | |||
sample variances, si^2 = | 2.194 | 1.000 | 0.500 | |||
total sum | 65 | 66 | 45 | 176 | (grand sum) | |
grand mean , x̅̅ = | Σni*x̅i/Σni = | 6.52 |
square of deviation of sample mean from grand mean,( x̅ - x̅̅)² | 0.495 | 0.664 | 2.306 | ||
TOTAL | |||||
SS(between)= SSB = Σn( x̅ - x̅̅)² = | 4.457 | 5.975 | 20.753 | 31.18519 | |
SS(within ) = SSW = Σ(n-1)s² = | 17.556 | 8.000 | 4.000 | 29.5556 |
SS | df | MS | F | p-value | F-critical | |
Between: | 31.19 | 2 | 15.59 | 12.66 | 0.0002 | 5.61 |
Within: | 29.56 | 24 | 1.23 | |||
Total: | 60.74 | 26 |
b)
critical value = 5.61
test statistic = 12.66
Decision: ---Select--- Reject H0
c) Compute the corresponding effect size(s) and
indicate magnitude(s).
η2 = SSB/ SST
= 31.19/ 60.74
= 0.5134
large effect
d)
At least one of the sessions differ on anxiety.
e)
µ1-µ2 | -0.11 | 1.68 | -1.79 | 1.57 | Not Significant means are not different |
µ1-µ3 | 2.22 | 1.68 | 0.54 | 3.90 | Significant means are different |
Thanks in advance!
revert back for doubt
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