are used to inoculate the gut of 20
gnotobiotic (germ-free) mice, 10 with each separate community The gut microbial
community from an obese and a lean mouse are harvested for subsequent
transplantation. These two communities. After two weeks the increase in body fat of
the mice and energy content of fecal samples are measured.
the two possible hypotheses about the possible outcomes of this
experiment. Frame this in the context of
b) The following
results were obtained:
S1: Mice with microbial community
from obese source
S2: Mice with microbial community
from lean source
Bomb calorimetry of the faecal gross energy content (kcal g-1)
S1 =[3.2316, 3.1642, 3.0398,
3.0568, 3.0186, 3.0991, 3.0324, 2.9469, 3.1815, 3.1593]
S2 =[3.2661, 3.1444, 3.4979,
3.8173, 3.3540, 3.4254, 3.4319, 3.7482, 3.5888, 3.3160]
Increase in total body fat (%)
S1 =[34.7751, 82.0402,
66.8450, 28.6254, 111.9754, 86.4072, 14.9222, 39.1467, 49.1888, 81.6303]
S2 =[34.2439, 36.3036,
32.3342, 24.2585, 42.9152, 45.0858, 34.7660, 27.5398, 32.4703, 25.1005]
Determine the sample means and variance. Plot the
t-distributions for the sample means given the statistics you calculate.
Use two-tailed unpaired t-tests to determine whether the
source of the gut flora inoculums made a difference. i.e. compare the two sets
of data for each measured quality: faecal gross energy content and increase
in total body fat. Use a level of significance of 0.05 and assume that
the quantities are normally distributed.
c) What are the P-values for the two different sets of data?
Provide an explanation for what these P-values mean in each case.
is another potential quality of the mice to test?