Statistics question from The Analysis of Biological Data 16

Statistics question from \"The Analysis of Biological Data\".

16. Not all telephone polls carried out to estimate
voter or consumer preferences make calls to cell
phones. One reason is that in the USA, automated
calls (“robocalls”) to cell phones are not
permitted and interviews conducted by humans
are more costly.
a. How might the strategy of leaving out cell
phones affect the goal of obtaining a random
sample of voters or consumers?
b. Which criterion of random sampling is most
likely to be violated by the problems you
identifi ed in part (a): equal chance of being
selected, or the independence of the selection
of individuals?
c. Which attribute of estimated consumer preference
is most affected by the problem you
identifi ed in (a): accuracy or precision?

19. In each of the following examples, indicate
which variable is the explanatory variable and
which is the response variable.
a. The anticoagulant warfarin is often used as
a pesticide against house mice, Mus musculus.
Some populations of the house mouse
have acquired a mutation in the vkorc1 gene
from hybridizing with the Algerian mouse,
M. spretus (Song et al. 2011). In the Algerian
mice, this gene confers resistance to
warfarin. In a hypothetical follow-up study,
researchers collected a sample of house mice
to determine whether presence of the vkorc1
mutation is associated with warfarin resistance
in house mice as well. They fed warfarin
to all the mice in a sample and compared
survival between the individuals possessing
the mutation and those not possessing the
mutation.
b. Cooley et al. (2009) randomly assigned
either of two treatments, naturopathic care
(diet counseling, breathing techniques,
vitamins, and a herbal medicine) or standardized
psychotherapy (psychotherapy with
breathing techniques and a placebo added),
to 81 individuals having moderate to severe
anxiety. Anxiety scores decreased an average
of 57% in the naturopathic group and 31% in
the psychotherapy group.
c. Individuals highly sensitive to rewards tend
to experience more food cravings and are
more likely to be overweight or develop
eating disorders than other people. Beaver
et al. (2006) recruited 14 healthy volunteers and scored their reward sensitivity using a
questionnaire (they were asked to answer yes
or no to questions like: “I’m always willing
to try something new if I think it will be
fun”). The subjects were then presented with
images of appetizing foods (e.g., chocolate
cake, pizza) while activity of their fronto–
striatal–amygdala–midbrain was measured
using functional MRI. Reward sensitivity of
subjects was found to correlate with brain
activity in response to the images.
d. Endostatin is a naturally occurring protein
in humans and mice that inhibits the growth
of blood vessels. O’Reilly et al. (1997)
investigated its effects on growth of cancer
tumors, whose growth and spread requires
blood vessel proliferation. Mice having lung
carcinoma tumors were randomly divided
into groups that were treated with doses of
0, 2.5, 10, or 20 mg/kg of endostatin injected
once daily. They found that higher doses of
endostatin led to inhibition of tumor growth.

20. For each of the studies presented in problem 19,
indicate whether the study is an experimental or
observational study.

Solution

16 a) The sample obtained by leaving out the cell phone would not be SRS it would be a biased sampling or judgemental sampling as sample is not taken from the entire population

16 b) Equal chance of beign selected is voilated by the problem identified

16 c) Accuracy would be affected by the problem identified

19a) The anticoagulant warfarin is the explanatory variable and survival of the mice is the response variable

19 b) The two treatments assigned to people naturopathic and standardised pshycotheraphy are explanatory varaible and anxiety is response variable

19c) Image of the appetizer is explanatory variable and Reward sensitivity of the person along with its brain activity is response variable

19 d) Dose of endostatin is independent variable and inhibition of tumor growth is response varibale