STA 3024
Homework 2
Section 7459
Form C
Name:
UFID:
This form is only for students whose UFID number begins with 6 or 7.
Answer all problems
neatly
. If you turn in more than one piece of paper, they must be
stapled
. Work
that isn’t neat or stapled may lose points. You don’t need to turn in this problem listing, but you do need
to include your
name
,
UFID number
, and
form code
on your homework.
For each of the following problems, do the following:
•
State the best type of inference method to use (from the ones covered in the Review 2 slides on the
website).
•
State the assumptions and whether or not they are satisfied. Irrespective of whether or not you think
they are satisfied, perform the analysis. The only assumption you may assume true if not stated is
randomization.
•
Perform a hypothesis test, stating the assumptions, teststatistic value, pvalue, and conclusion. Inter
pret the conclusion in the context of the problem.
•
If we went over a confidence interval corresponding to the method you chose, make the 95% confidence
interval. Interpet it in the context of the problem. State whether or not you reach the same conclusion
from the hypothesis test as the confidence interval.
3 problems
×
12 points
2 problems
×
4 points (2 points for right method, 2 points completion)
44 points total
1.
total points: 4
It was mentioned in class that the ttest is named for a statistician called Student
(William Sealy Gosset). In his seminal paper, “The Probable Error of a Mean” (1908), data on barley
were included to illustrate the method he introduced. You may assume that the values follow a normal
distribution.
Each location the barley was harvested from was split into two batches, one that was
dried in a kiln and one that was not. Is there evidence that Kiln Dried barley performs better (larger
average) than Not Kiln Dried barley at
α
= 0
.
10?
Not Kiln Dried
1903
1935
1910
2496
2108
1961
2060
1444
1612
1316
1511
Kiln Dried
2009
1915
2011
2463
2180
1925
2122
1482
1542
1443
1535
It may help to know that the average for the Kiln Dried is 1875.18, the average for the Not Kiln Dried is
1841.46, and the standard deviation of the pairwise differences is 66.17.
Best Inference Method
2 points
Two sample matchedpairs ttest
Assumptions
•
Data obtained from randomization
•
The sample of differences is a random sample from a population of differences
1
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Quantitative response variable
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 Spring '08
 TA
 Statistics, Normal Distribution, Null hypothesis, Wilcoxon signedrank test, Rick Perry

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