Stat 2000: Tips for Assignment 1
Published: Sat, 01/14/12
Hi ,
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I would appreciate your input as to the date of the midterm exam prep seminar for Stat 2000. Since the midterm exam is on Saturday, March 3, I intend to offer the seminar on the weekend of Feb. 25 or 26. That is the weekend at the end of the midterm break. Would you prefer the seminar to be on Saturday, Feb. 25 or Sunday, Feb. 26 or does it matter? Keep in the mind the seminar will be 9 am to 9 pm on the day. I could also be convinced to offer the seminar on the weekend of Feb. 18 or 19 at the start of the midterm break if that suits students better. Please let me know your plans for midterm break and if you have an opinion about the seminar date.
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If you are taking the course by classroom lecture (Sections A01, A02, etc.), click here for my tips for your Assignment 1.
You need to study Lessons 1, 2 and 3 in my book (if you have it) to prepare for this assignment. I suggest you study Lesson 1, then attempt question 1. Study Lesson 2, then attempt question 2. You will need to study Lesson 3 before you are ready to attempt the rest of the assignment.
Question 1 is good run-through of all the concepts I teach in Lesson 1 of my book.
Question 2 has chosen an unusual level of confidence so be sure to study question 10 in Lesson 1 of my book to understand how to get the appropriate critical value. Make sure you have read the Appendix at the back of my book to learn how to use your calculator's Stat mode to get the mean and standard deviation of the data set (of course, you have been given the population standard deviation, so you don't really need the sample standard deviation). Lesson 2 in my book teaches you how to conduct a hypothesis test.
Never use JMP to answer a question unless they specifically tell you to. Whenever
they do tell you to use JMP, never go out of your way to click red
triangles to add things to the graph (like put titles on histograms, or
label axes). Whatever JMP gives by default is all they require unless
they specifically request you add something to the output or remove
something from it. Of course, I will always give you specific steps to
add/remove anything they do require.
To get JMP to make confidence intervals and test hypotheses for the mean:
First, open JMP and select "New Data Table". Double-click Column 1 and give it an appropriate name for the data set (like "lifetime"). Type the given data down column 1, using your Tab or Arrow keys on your keyboard to move down each cell.
Select Analyze,
Distribution from the toolbar at top. Highlight the column you are
interested in and click the "Y, Columns" button. Click OK. You are now
taken to a window showing a histogram and stuff.
To get a confidence
interval, click the red triangle next to your column variable directly
above the histogram to get a drop-down list and select "Confidence
Interval". In the pop-up window that appears, select "Other" (even if
the level of confidence you desire is in the list) and type in the level
of confidence you want (in decimal form, so 95% is 0.95). Make sure
"Two-sided" is selected. If you are given a value for sigma, the
population standard deviation, select the "Use known Sigma" checkbox.
Click OK. You will get another pop-up window where you can type in your
known value for sigma (if you selected that option). A Confidence
Intervals table will appear in your output screen at the bottom.
To
test a hypothesis, click that same red triangle you used to make a
confidence interval and select "Test Mean". Type in the value the null
hypothesis believes the mean to be and type in the known value of sigma
if you have one (otherwise leave that value blank). Click OK. A "Test
Mean = Value" table appears in your output where, among other things,
JMP gives you the test statistic and three probability values. Those
three probabilities are the P-value for the three possible alternative
hypotheses. JMP will use a z statistic if you are given a sigma value
to enter or a t statistic if sigma is unknown.
Prob > |z| or Prob > |t| is the two-tailed P-value.
Prob > z or Prob > t is the upper-tailed P-value.
Prob < z or Prob < t is the lower-tailed P-value.
Questions 3 to 6 are a good run-through of the concepts I teach in Lesson 3 of my book.
Questions 7 and 8 return to Lessons 1 and 2 in my book. (What is the key difference between these two questions and the first two questions of the assignment?) See my tips above to help with the JMP part.
Study Lessons 1 and 2 in
my study book (if you have it) to learn the concepts involved in HW1.
It is essential that you take the time to get a thorough understanding
of Lessons 1 and 2 first. That will set you up for the whole course.
The student who struggles in those concepts will never be able to
progress. The student who feels comfortable with these lessons, will
find that the rest of the course flows at a smooth and steady pace.
Note that this entire assignment uses z, not t since they always give you the population standard deviation, σ.
Ignore any references to JMP 6SE or Crunchit!.
You are using JMP 8 in this course. The assignment is just an old
assignment that they forgot to update. Use JMP 8 anytime they tell you
to use computer stuff.
Question 5 part a is
using the formulas for mean and standard deviation I teach at the start
of Lesson 6 in my study book. Read the first few pages and try
questions 1 and 2 to help you prepare for this assignment question. The
rest of question 5 uses the properties for mean and variance I teach inLesson 4 of my study book (this is only recent editions of my
book, white or blue covers). Again, you need to only look at the first couple of
questions I do in Lesson 4 to assist with this question. Leave thorough study of Lessons 4 and 6 until later on in this course.
Question 6 is using the formulas for confidence interval for a mean and sample size determination I teach in Lesson 1 of my book.
Question 7:
To copy and paste data into JMP 8,
first open JMP and select "New Data Table". To make sure the column
headings are pasted properly, select and copy the data, then be sure to
select "Edit" in the JMP toolbar and select "Paste with column names".
Then your data should paste properly. JMP has a nasty habit of messing
up when this is done, though. If your column contains numbers
(quantitative data), make sure you double-click each column heading and
confirm that the Data Type is Numeric and the Modeling Type is
Continuous (JMP may have changed the Data Type to Character and the
Modeling Type to Nominal).
To get JMP to make confidence intervals for the mean:
Select Analyze, Distribution from the toolbar at
top. Highlight the column you are interested in ("drp" in this case)
and click the "Y, Columns" button. Click OK. You are now taken to a
window showing a histogram and stuff. To get a confidence interval,
click the red triangle next to your column variable directly above the
histogram to get a drop-down list and select "Confidence Interval". In
the pop-up window that appears, select "Other" (even if the level of
confidence you desire is in the list) and type in the level of
confidence you want (in decimal form, so 95% is 0.95). Make sure
"Two-sided" is selected. If you are given a value for sigma , the
population standard deviation, (and you are in this question) select the
"Use known Sigma" checkbox. Click OK. You will get another pop-up
window where you can type in your known value for sigma. A Confidence
Intervals table will appear in your output screen at the bottom.
To get JMP to test hypotheses for the mean:
To test a hypothesis, click that
same red triangle you used to make a confidence interval and select
"Test Mean". Type in the value the null hypothesis believes the mean to
be and type in the known value of sigma, if you have one (otherwise
leave that value blank). Click OK. A Test Mean = Value table appears
in your output where, among other things, JMP gives you the test
statistic and three probability values. Those three probabilities are
the P-value for the three possible alternative hypotheses. JMP will use
a z statistic if you are given a sigma value to enter or a t statistic
if sigma is unknown.
Prob > |z| or Prob > |t| is the two-tailed P-value.
Prob > z or Prob > t is the upper-tailed P-value.
Prob < z or Prob < t is the lower-tailed P-value.
To get rid of any outputs you don't want to copy and paste, click the red triangle and deselect the unwanted things.
To copy and paste the parts of a JMP printout you do want,
select the icon on the JMP toolbar that looks like a fat white plus
sign "+" (the Selection tool). You can then click various parts of the
printout to select the sections you want. Copy and paste into Word or
something like that.
Note, you must save your document as a PDF file to
upload it into Web Assign (no other format will be accepted; do not save upload files as "doc" files like it says in your assignment; save as "pdf" files!). If you
don't know how to do this for the software you are using try the help
files or Google "save as pdf file" for some helpful steps or programs
that enable you to save documents that way for free. MS Word 2007 or newer is
capable of saving as pdf. If you are using a different program and do
not have a "save as pdf" option, Google "pdf995 download" for a free
program that can be used to save documents in a pdf format. Note that,
if you are using a program like this, often it loads a "pdf printer"
onto your computer. Then, to save your file as pdf, you actually select
"print" as though you were going to print your file, then select your
"pdf printer" rather than your physical printer in the print options.
That will then save your file in pdf form.
Question 8:
If you are making a confidence
interval by hand and have to use an unusual level of confidence, look at
my question 10 in Lesson 1 for an example how to do that. Also be sure
to study how to compute a P-value and test a hypothesis in Lesson 2 of
my book. Note, if you are computing a P-value, you can skip Step 2 in
my steps to test a hypothesis.