In: Statistics and Probability
Scientist warn that food shortages are an impending future issue
for humans. A potential solution is eating non-traditional foods in
the western world. An experimental psychologist knows that
westerners are uncomfortable eating food other cultures have no
trouble eating. The psychologist developed a method to help
individuals tolerate more the eating of non-ordinary food. However,
the psychologist is unsure which type(s) of foods the method will
be more effective on. The psychologist has some participants go
through the method and then asks them to eat each of the following
out of the ordinary foods: stick insects, bovine testicles, fish
eyes, and Witchetty grubs. On each occasion, participants are
measured on how many seconds it takes before they gagged while
eating the food. The data are in the table below. What can the
psychologist concluded with α = 0.01?
stick | bovine | fish | grub |
7 8 6 4 8 7 9 11 |
6 4 1 2 3 4 1 5 |
1 2 3 1 4 4 6 7 |
5 4 7 8 7 6 1 0 |
a) What is the appropriate test statistic?
---Select--- na one-way ANOVA within-subjects ANOVA two-way
ANOVA
b) Input the appropriate value(s) to make a
decision about H0.
p-value =_______________ ;
Decision: ---Select--- Reject H0 Fail to reject H0
c) Using the SPSS results,
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.
1) At least one of the foods differed on time before gagging.
2) None of the foods differed on time before gagging.
1)
one-way ANOVA
2)
count, ni = | 8 | 8 | 8 | 8 | |
mean , x̅ i = | 7.500 | 3.25 | 3.50 | 4.75 | |
std. dev., si = | 2.070 | 1.832 | 2.204 | 2.92 | |
sample variances, si^2 = | 4.286 | 3.357 | 4.857 | 8.500 | |
total sum | 60 | 26 | 28 | 38 | 152 |
grand mean , x̅̅ = | Σni*x̅i/Σni = | 4.75 |
square of deviation of sample mean from grand mean,( x̅ - x̅̅)² | 7.563 | 2.250 | 1.563 | 0.000 | |
TOTAL | |||||
SS(between)= SSB = Σn( x̅ - x̅̅)² = | 60.500 | 18.000 | 12.500 | 0.000 | 91 |
SS(within ) = SSW = Σ(n-1)s² = | 30.000 | 23.500 | 34.000 | 59.500 | 147.0000 |
no. of treatment , k = 4
df between = k-1 = 3
N = Σn = 32
df within = N-k = 28
mean square between groups , MSB = SSB/k-1 =
30.3333
mean square within groups , MSW = SSW/N-k =
5.2500
F-stat = MSB/MSW = 5.7778
P value = 0.0033
conclusion : p-value<α , reject null
hypothesis
3)
Effect Size = SSR / SST
= 91 / 238
= 0.3824
LARGE
4)
1) At least one of the foods differed on time before gagging.
Thanks in advance!
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