PS7002 Retake Test (2018) - Desklib

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PS7002 retake test (2018)
PS7002 Take home retake test
June 2018
Name KU Number
There are 4 questions, each worth 25 marks. Please try to answer all of the questions. Have a
look through the test and make sure you know how many questions there are and what areas
submit this document on Canvas. APA style should be used throughout for reporting descriptive
and inferential statistics. If you have any questions, don’t hesitate to ask.
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PS7002 retake test (2018)
QUESTION 1
Researchers tested the effects of a new treatment of anxiety. In their study, anxious individuals
received varying amounts of the treatment and subsequent anxiety levels were compared to
those of a control group (individuals on a waiting list for treatment). Twenty participants were
randomly assigned to one of four treatment groups; each group received a different number of
treatment sessions: i) control (no treatment); ii) 1 treatment session; iii) 5 treatment sessions; or
iv) 10 treatment sessions. The SPSS output for the data analysis is shown below.
a) What type of test was used to analyse the data? (2 marks)
“Planned comparison and pro-hoc test” is applied here for analysing the data set. The analysis
focuses on establishing the equality of means of anxiety levels of four treatment sessions that
are ‘control’, ‘1 treatment session’, ‘5 treatment sessions’ and ‘10 treatment sessions’. It tests an
overall difference between ‘conditions’, evaluating whether averages differ or not.
b) Has the assumption of homogeneity of variance been met? (3 marks)
The significant p-value of the ‘Levene Statistic’ is 0.711 which is greater than 0.05. Therefore,
the null hypothesis of unequal variances is accepted with 95% probability. Therefore, the
assumption of homogeneity of variance has been met.
c) Report the results of the analysis by first reporting the descriptive statistics and then the
inferential statistics (using APA style) (4 marks for reporting the descriptive statistics and 4
marks for reporting the inferential statistics).
The descriptive statistics refers that ‘Control’ group has highest average anxiety level (33.6)
followed by ‘One session’ (32.8). The ‘10 sessions’ group has lowest average anxiety level
(20.4). The scatter-ness in terms of standard deviation is highest in ‘One session’ group (6.301)
and least in ‘10 session’ group (4.037). The range of ‘anxiety level’ is maximum in the ‘One
session’ group (24 to 41).
The ANOVA table suggests that- the p-value of F-statistic (8.288) with (3, 16) degrees of
freedom is 0.001. The calculated p-value is less than 0.05. Hence, the null hypothesis of equality
of averages of all the four groups of anxiety is rejected with 95% probability. That is why, we
can infer that, there exists at least one group whose average anxiety level is significantly
different from the others. Therefore, all the groups have equal average anxiety level (Source:
Laerd Statistics., 2018).
Besides, the contrast 1 and contrast 2 indicates that the its significance (p-value less than 5%).
However, the contrast 3 is insignificant (p-value greater than 5%).
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PS7002 retake test (2018)
d) What do the planned comparisons reveal about the effectiveness of the treatment for anxiety?
And what should researchers recommend to clinicians: how many treatment sessions would be
most effective? (12 marks)
Multiple comparisons are executed in the absence of defined hypotheses earlier. It is executed
with the help of ‘pro-hoc’ test. ‘pro-hoc’ tests are used to compare mean against each other. The
planned comparisons reveal that the effectiveness of the treatment for anxiety are unequal to
each other.
The p-value of t-statistic (-3.005) for ‘Contrast 1’ is 0.008 (<0.05) and p-value of t-statistic (-
3.817) ‘Contrast 2’ is 0.002 (<0.05). The p-values generated from pro-hoc tests of the contrasts
show that ‘Contrast 1’ and ‘Contrast 2’ have statistical non-significance for the assumption of
equal variances. The p-value of t-statistic (1.123) for ‘Contrast 3’ is 0.278 (>0.05). It shows that
contrast 3 does not have any statistical significance for the assumption of equal variances at 5%
level of significance.
The number of effective treatment sessions (Calculated from F-statistic) is 0.584.
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PS7002 retake test (2018)
QUESTION 1 SPSS OUTPUT
Descriptives
Anxiety
N Mean
Std.
Deviation
Std.
Error
95% Confidence Interval
for Mean
Minimu
m
Maximu
m
Lower
Bound
Upper
Bound
Control 5 33.60 5.030 2.249 27.35 39.85 29 40
One session 5 32.80 6.301 2.818 24.98 40.62 24 41
Five
sessions
5 24.00 4.637 2.074 18.24 29.76 18 31
Ten sessions 5 20.40 4.037 1.806 15.39 25.41 16 26
Total 20 27.70 7.435 1.662 24.22 31.18 16 41
Test of Homogeneity of Variances
Anxiety
Levene
Statistic df1 df2 Sig.
.464 3 16 .711
ANOVA
Anxiety
Sum of Squares df Mean Square F Sig.
Between Groups 639.000 3 213.000 8.288 .001
Within Groups 411.200 16 25.700
Total 1050.200 19
Robust Tests of Equality of Means
Anxiety
Statistica df1 df2 Sig.
Welch 8.034 3 8.800 .007
Brown-Forsythe 8.288 3 14.358 .002
a. Asymptotically F distributed.
Contrast Coefficients
Contrast
Treatment_group
Control One session Five sessions Ten sessions
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