Solved by a verified expert:BIOL 301 PROBLEM SET 4 (170 pts)
ANOVA, CORRELATION, REGRESSION,
and cumulative problems
Your
answers to these questions are due in my office anytime before 11:00AM Tuesday May
19th. If they are turned in
late you will lose 10% per day. So, if you turn it in at 11:01, you lose 10%
immediately.
Here
are the general rules. READ THEM
CAREFULLY!
·
All precepts of the Honor Principle apply.
·
This is an “open book” assignment. You
may consult any printed text or online resource you like in preparing your
answers. However, you mustwork completely independently –
you may not communicate with anyone except the professor about this assignment,
in any way. Period.
·
How to get help. If you have questions, please
email me or come to an office hour. I will
try my best to email you back as soon as I can.
·
Read through the entire assignment before you start. Make sure you
understand what is being asked. Ask if
you’re not sure about a question. Follow
directions very carefully. Complete
sentences and typing are needed only where specifically requested.
·
Neatness and professionalism count for 4 points on
this assignment. Use, blue pen, or
black pen for your handwritten answers.
You may want to formulate your handwritten responses on a separate sheet
(or a photocopy of the assignment), then transfer them over when you are
satisfied with your answers. However, if
you must type, your answer must fit into the allotted page. Collate the pages
for each question together as instructed, then staple all of the pages
together. If you must, use
a computer, DO NOT CHANGE THE FORMATTING. That is keep EVERYTHING (i.e., the
Question I. A., B., etc.) that is already on the problem set!
·
Make sure you do not exceed the allotted space. Answers must fit within the blank space provided. Typewritten answers must fit within the
space/font limits.
·
For full credit you will need to show or tell how you
obtained your answer. If you use Excel or R for problems that require
calculations, you may want to explain exactly what you did, attach annotated
output, or attach a program so that I can give partial credit if needed.
·
Only put
answers where they belong; do not change the number scheme, order, etc.
·
The number of points you obtain on a question will
depend on how thorough your procedures and answers to the questions are. For
example, remember to include units for those measures for which units are
needed, correctly label axes, include figure legends that are appropriate,
descriptive and clear. If you perform a
hypothesis test, make sure to include the test statistic, the df, and the P
value. Remember to state your assumptions clearly and explicitly. Parts of this assignment are designed to
mimic the situations you will face in the practical application of
statistics. I expect you to apply all
approaches that are necessary to address the problem, and to know when a
specified approach is not appropriate.
·
Do not worry about redundancy in answers within a
question, except on the essay and write-up questions. It’s
ok to repeat material across parts of the other questions.
QUESTION I – SHORT-ANSWER ESSAY (10 pts)
Your answer to this
question should be handwritten or typed on this page in the space provided (12
pt font, double-spaced, <250 words).
It is critical that you understand the process of
statistical inference and be able to explain it even to someone who knows no
statistics. Provide a verbal description
of what statistical inference is and how it works; you may also include a small
figure or sketch to supplement your text.
Be sure to avoid statistical jargon and to use your own words. Do not just parrot back the textbook.
QUESTION II – (10 pts)
You answer to this question should
be handwritten or typed on this page and should not exceed the length available
below. Write your answer as if you are preparing a formal statistical report
suitable for publication in a scientific journal.
Researchers in Britain asked a few
hundred people about their daily coffee intake. Of
the 22 people from that group who
had the highest coffee intake, nine of them reported
hearing voices sometimes when no
other person was present. Of the 22 people with the
lowest coffee intake, three people
reported sometimes hearing voices.
A. Doan appropriate hypothesis test to
investigate a possible link between coffee intake and hearing voices. Be sure
to provide a clearly worded statement of your conclusion.
B. Are the
results from part (a) sufficient evidence to support the statement that
coffee drinking sometimes causes people to hear voices? Why, or why not?
QUESTION III: Experimental
design (15 pts)
During my postdoctoral work, I performed an experiment
looking at the effects of predators on the activity of damselfly larvae. For this experiment, I included 20
individuals of one species. The
experiment was done in a small container inside a larger container. The predator, a big, mean fish, was prevented
from attacking the damselfly by placing the damselfly in the smaller inner compartment,
and placing the fish in the larger outer compartment of the container. The walls of the containers were made of
plexiglas, so the damselfly could see the fish to know whether it was there.
To conduct the experiment, I would take a randomly selected
larva, put the larva in the inner container, allow it to acclimate for 15
minutes, and then record from behind a blind all behaviors that it performed in
a 45 minute observation period. After
this, the larva was removed from the container and placed back in its holding
container for 24 hours, and then the next day repeat the same procedure, except
for putting the fish in the outer compartment.
Address the following
questions regarding this experiment:
A)
What is wrong with this experiment?
B)
How should this experiment be done
correctly?
C) How does this flaw affect the conclusions that can be drawn from the
experiment
QUESTION IV
– (29 points)
Kudzu
is a plant that was imported into the US from Japan and now covers over 7
million acres in the southern US. The
plant is generally considered a huge nuisance from ecological, forestry, and
agricultural perspectives, but it may have a redeeming feature: it contains chemicals called isoflavones that
have been shown to have beneficial effects on bones. Professor Strongbones used a completely
randomized experiment to compare three groups of rats: a control group + groups that were fed either
a low dose or a high dose of isoflavones from kudzu for 2 months. You may assume that appropriate randomization
procedures were used to select rats for each treatment. At the end of the experiment, one of the
response variables was the bone mineral density (BMD) in the femur (in grams
per square centimeter) of each rat: see
the dataset Kudzu.
Is there an effect of kudzu isoflavones
on the BMD of rat femurs that might justify further research (and perhaps
vindicate the presence of kudzu on the landscape)?
Please state the null and alternative hypotheses
for this analysis, as formally as you can
Prepare an appropriate graph presenting these
data, similar to what might appear in a published paper. Thus, this figure should allow you to
visually display the comparisons you are making statistically. Your graph
should have only one panel, be labeled appropriately, and include a
caption. Put your graph and caption
on a separate page to be included immediately following this page. In
the space below, please also explain briefly why you chose the particular
graph that you did. HINT: You may want to work through all of the
questions involving this dataset before you design this figure!
QUESTION IV,
continued
What are the major assumptions you need to make
in order to test the null hypothesis?
Do the data meet these assumptions?
Summarize your findings in the table below and provide evidence to
support your claims on the next page, if needed; be sure to reference this
evidence in your answers. (You may not need all of the rows in the table.)
(10 pts)
Assumption
Do these
data meet that assumption?
Bottom
line: is it appropriate to do your
proposed analysis on this dataset?
Circle one: YES/NO
Briefly explain your answer:
Please
do not write below this line
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