Which one of the following statements is a correct interpretation of the output from the t-test given in Table 1.   There is evidence that the underlying mean of BrainChange is negative. It is not plausible that the underlying mean of BrainChange is positive. There is evidence against μNoInt being 0. It is plausible that the underlying mean of BrainChange is 0. It is not plausible that μNoInt is 0.

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Which one of the following statements is a correct interpretation of the output from the t-test given in Table 1.

 
  • There is evidence that the underlying mean of BrainChange is negative.
  • It is not plausible that the underlying mean of BrainChange is positive.
  • There is evidence against μNoInt being 0.
  • It is plausible that the underlying mean of BrainChange is 0.
  • It is not plausible that μNoInt is 0.
Brain size typically shrinks as people age and such shrinkage may be linked to dementia. A study was done in
China to investigate whether different types of activity might help to prevent brain shrinkage or perhaps even lead
to an increase in brain size.
The 80 (non-demented) volunteers were aged between 60 and 69. Each of them had an MRI to determine brain
size before the study began. They were then randomly allocated to one of three activity groups: TaiChi, Social or
Nolntervention.
Except for the Nolntervention group, the groups met with their leaders three times a week over a period of 40
weeks. The NoIntervention group were called four times by the study coordinator during the study period.
At the end of the study, the participants had another MRI and the percentage change in size of each participant's
brain was calculated.
Adapted from: Mortimer, J. A., Ding, D., Borenstein, A. R., DeCarli C., Guo, Q., Wu, Y., Zhao, Q. and Chu, S.
(2012), Changes in Brain Volume and Cognition in a Randomized Trial of Exercise and Social Interaction in a
Community-Based Sample of Non-Demented Chinese Elders.
The two variables used are defined as:
Activity
BrainChange Percentage change in size of participant's brain
oo
The activity the participant was randomly assigned to
- TaiChi
(meet two Tai Chi masters to practise Tai Chi)
- Social
Questions 8 and 9 refer to the following additional information.
-2
(meet at a community centre to discuss interesting topics)
- NoIntervention
(no activity assigned)
A plot of BrainChange for the participants who were assigned to the Nolntervention group is shown in Figure 1.
The mean is indicated by the triangle.
(where a positive value means the brain increased in size)
NoIntervention
ooo 0 00 8
NoIntervention
-1
N
24
O
0
BrainChange
Figure 1: BrainChange for the NoIntervention group
Let uNoInt be the underlying mean BrainChange when there is no activity assigned.
A one-sample t-test with hypotheses Ho: "NoInt = 0 vs H₁ : NoInt 0 was conducted to investigate whether
there was an underlying mean BrainChange when there was no intervention. The output for this test is shown in
Table 1.
One-Sample Statistics
t
-.935
O
df
23
O
O
00 00
Mean Std. Deviation Std. Error Mean
-.2401
1.25843
.25688
One-Sample Test
00 O
Test Value = 0
2
Sig. (2-tailed) Mean Difference
.360
-24012
95% Confidence Interval of the
Lower
-.7715
Difference
Upper
2913
Transcribed Image Text:Brain size typically shrinks as people age and such shrinkage may be linked to dementia. A study was done in China to investigate whether different types of activity might help to prevent brain shrinkage or perhaps even lead to an increase in brain size. The 80 (non-demented) volunteers were aged between 60 and 69. Each of them had an MRI to determine brain size before the study began. They were then randomly allocated to one of three activity groups: TaiChi, Social or Nolntervention. Except for the Nolntervention group, the groups met with their leaders three times a week over a period of 40 weeks. The NoIntervention group were called four times by the study coordinator during the study period. At the end of the study, the participants had another MRI and the percentage change in size of each participant's brain was calculated. Adapted from: Mortimer, J. A., Ding, D., Borenstein, A. R., DeCarli C., Guo, Q., Wu, Y., Zhao, Q. and Chu, S. (2012), Changes in Brain Volume and Cognition in a Randomized Trial of Exercise and Social Interaction in a Community-Based Sample of Non-Demented Chinese Elders. The two variables used are defined as: Activity BrainChange Percentage change in size of participant's brain oo The activity the participant was randomly assigned to - TaiChi (meet two Tai Chi masters to practise Tai Chi) - Social Questions 8 and 9 refer to the following additional information. -2 (meet at a community centre to discuss interesting topics) - NoIntervention (no activity assigned) A plot of BrainChange for the participants who were assigned to the Nolntervention group is shown in Figure 1. The mean is indicated by the triangle. (where a positive value means the brain increased in size) NoIntervention ooo 0 00 8 NoIntervention -1 N 24 O 0 BrainChange Figure 1: BrainChange for the NoIntervention group Let uNoInt be the underlying mean BrainChange when there is no activity assigned. A one-sample t-test with hypotheses Ho: "NoInt = 0 vs H₁ : NoInt 0 was conducted to investigate whether there was an underlying mean BrainChange when there was no intervention. The output for this test is shown in Table 1. One-Sample Statistics t -.935 O df 23 O O 00 00 Mean Std. Deviation Std. Error Mean -.2401 1.25843 .25688 One-Sample Test 00 O Test Value = 0 2 Sig. (2-tailed) Mean Difference .360 -24012 95% Confidence Interval of the Lower -.7715 Difference Upper 2913
Table 1: One-sample t-test output
Questions 10 to 14 refer to the following additional information.
A one-way analysis of variance (ANOVA) F-test was conducted to investigate the relationship between Activi
and BrainChange.
Let
Tai be the underlying mean BrainChange
when the activity is TaiChi
"Soc be the underlying mean BrainChange
when the activity is Social
and recall that
"NoInis the underlying mean BrainChange
when there is no activity assigned.
The plot of BrainChange by Activity is shown in Figure 2 (with each group mean being indicated by a
triangle) and the output from the F-test is shown in Table 2.
TaiChi
Social
NoIntervention
00
-2
BrainChange
TaiChi
Social
Total
NoIntervention
O
Figure 2: BrainChange by Activity
BrainChange
Between Groups
Within Groups
Total
O OOD O
(1) Treatment
TaiChi
Social
O
Sum of
Squares
7.820
00
N
Mean
29 4711
27 4056
24 -2401 1.25843
80
Std.
Deviation
.85575
69690
2356
98967
69.556
77.376
Dependent Variable: BrainChange
Tukey HSD
(J) Treatment
Social
TaiChi
Nolntervention
Nolntervention TaiChi
Social
0 0 0 0
Note that one of the values has been replaced with ++
Nolntervention
00
00
ANOVA
Descriptives
df
2
77
79
O
0
00
00 00
Std. Error
15891
13412
25688
.11065
8
Mean
Square
3.910
.903
000 00⁰ 00
0
BrainChange
0
Minimum
-1.83
-1.36
-2.03
-2.03
F
++
Multiple Comparisons
Mean Difference Std.
(1-J)
Error
.06544
.25418
.71119
.26227
-.06544
.25418
.64575
.26664
-.71119
.26227
-.64575
.26664
O co
0
Maximum
2.20
1.80
2.01
2.20
Sig.
.017
Sig.
.964
.022
.964
.046
.022
.046
00
00
0 0
1
O
00
0 0 0
O
.0844
-.6729
.0085
-1.3380
-1.2830
O
2
95% Confidence Interval
Lower Bound Upper Bound
-.5420
.6729
1.3380
.5420
1.2830
-.0844
-.0085
Transcribed Image Text:Table 1: One-sample t-test output Questions 10 to 14 refer to the following additional information. A one-way analysis of variance (ANOVA) F-test was conducted to investigate the relationship between Activi and BrainChange. Let Tai be the underlying mean BrainChange when the activity is TaiChi "Soc be the underlying mean BrainChange when the activity is Social and recall that "NoInis the underlying mean BrainChange when there is no activity assigned. The plot of BrainChange by Activity is shown in Figure 2 (with each group mean being indicated by a triangle) and the output from the F-test is shown in Table 2. TaiChi Social NoIntervention 00 -2 BrainChange TaiChi Social Total NoIntervention O Figure 2: BrainChange by Activity BrainChange Between Groups Within Groups Total O OOD O (1) Treatment TaiChi Social O Sum of Squares 7.820 00 N Mean 29 4711 27 4056 24 -2401 1.25843 80 Std. Deviation .85575 69690 2356 98967 69.556 77.376 Dependent Variable: BrainChange Tukey HSD (J) Treatment Social TaiChi Nolntervention Nolntervention TaiChi Social 0 0 0 0 Note that one of the values has been replaced with ++ Nolntervention 00 00 ANOVA Descriptives df 2 77 79 O 0 00 00 00 Std. Error 15891 13412 25688 .11065 8 Mean Square 3.910 .903 000 00⁰ 00 0 BrainChange 0 Minimum -1.83 -1.36 -2.03 -2.03 F ++ Multiple Comparisons Mean Difference Std. (1-J) Error .06544 .25418 .71119 .26227 -.06544 .25418 .64575 .26664 -.71119 .26227 -.64575 .26664 O co 0 Maximum 2.20 1.80 2.01 2.20 Sig. .017 Sig. .964 .022 .964 .046 .022 .046 00 00 0 0 1 O 00 0 0 0 O .0844 -.6729 .0085 -1.3380 -1.2830 O 2 95% Confidence Interval Lower Bound Upper Bound -.5420 .6729 1.3380 .5420 1.2830 -.0844 -.0085
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