Stat 2000 Distance: Assignment 1 Tips (Distance/Online Sections)
Published: Sat, 01/12/13
My tips for Assignment 1 are coming below, but first a couple of announcements.
Please note that my first review seminar for
Stat 2000 is likely to be on the weekend of Feb. 23 or 24 (one week before the midterm exam). Unfortunately, that means the seminar is the weekend at the end of the week-long Midterm Break, but it is out of my hands. This seminar will cover the lessons in Volume 1 of my book. More info will be sent later about this seminar when everything is finalized. I am not taking registrations for the seminar as of yet.
Did you read my Tips on How to Do Well in this Course?
Make sure you do: Tips on How to Do Well in Stat 2000
Did you read my Tips on what kind of calculator you should get?
If you are taking the course by Classroom Lecture (Sections A01, A02, etc.), I will send tips for Assignment 1 once it is posted.
Tips for Assignment 1 (Distance/Online Sections D01, D02, D03, etc.)
Study Lessons 1 and 2 in
my study book (if you have it) to learn the concepts involved in Assignment 1.
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.
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 that 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.
When you are answering questions in Web Assign, always answer one box at a time. Type your answer in the box (or select the correct response) and then click "Submit Answer" immediately. DO NOT answer several questions before you submit any answers. If you submit one answer at a time, you will make sure you are correct before you proceed and also prevent any glitches where things get submitted accidentally.
Note also that any question that requires you to upload a file is not being marked at that time. You can go back and upload a new file as many times as you wish up to the due date. Don't be confused by the message telling you to read such and such in the book. That is them just warning you that no one has marked your submission and you may want to double-check you understood the question and ensure what you have uploaded is correct.
Ignore any references to "Crunchit!" or JMP 6SE. You
are using JMP 10 in this course. The assignment is just an old
assignment that they forgot to update. Use JMP 10 anytime they tell you
to use computer stuff.
For the JMP 10 part of the assignment, here are some tips:
If you have not done so already, you need to download JMP to
your computer. Here is the direct link where you can get it (you need
to know your UMNET ID and password):
Once you have installed JMP 10 and opened it, you are shown
a
menu with various buttons to click. You will almost always click "New
Data Table" to enter new data. That is the icon on the far left of the
top toolbar (it looks like a tiny little spreadsheet with a yellow star,
point your mouse at it and you should see the label "New Data Table"
pop up.
In the rare event they have given you a
JMP file with the data already entered in it, you will simply open that
file which would probably already open JMP for you. Just click the
"Open" icon on the same toolbar as the "New Data Table" icon, or, if you
already see the file in the "Recent Files" screen, simply double-click
that. If you happen to
enter data in yourself and save the file (a good idea), you can select
"Open" to open up the saved file.
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. Do not study any more of Lesson 6 at this time! The
rest of question 5 uses the properties for mean and variance I teach in Lesson 4 of my study book (this is only recent editions of my
book, yellow, 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.
Note that the rest of this assignment uses z, not t since they always give you the population standard deviation, σ.
Question 7:
To copy and paste data into JMP 10,
first open JMP and select "New Data Table". Click the link they provide to get your data set, and select and copy the entire data set, including the column names. 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. 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 (given in part (b) of the question), and type in the known value of sigma, since 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. In your case, JMP better be using z.
Prob > |z| is the two-tailed P-value.
Prob > z is the upper-tailed P-value.
Prob < z is the lower-tailed P-value.
Again, be sure to read part (b) closely in order to understand whether you are doing a two-tailed, upper-tailed or lower-tailed test. JMP provides all three P-values because it does not know what your alternative hypothesis is.
To get rid of any outputs you don't want to copy and paste, click the red triangle and deselect the unwanted things. If you hold the CTRL key when you click the red triangle, you can deselect all the unwanted things at once. Alternatively, you can just select and copy the Confidence Interval and Test Mean = Value parts of the output they have requested.
You are now ready to copy and paste the output.
Click the thin blue line near the top of the window that has
the histogram, etc. to reveal the toolbar. Select the icon that
looks
like a fat white cross or plus sign "+". This is your "Selection"
tool. Your mouse cursor should now have changed from an arrow to that
white cross. Click the title bar that says "Distribution..." at the top
of the output and that should select the entire output (graph,
etc.). You can also experiment with the Selection Tool and try
selecting just the Confidence Interval and Test Mean sections, if you wish, since that is all they
request (that is not mandatory though). Try holding the CTRL key while selecting desired parts of the output. Once you have selected the
output, right-click and select Copy.
They have not requested that you discuss anything about the outputs, so you are now ready to save the document and upload it. DO NOT save the document as a "doc" or "docx" file. You must save the document as a pdf file! Again, this is a typo in your assignment to suggest otherwise.
You are now ready to save and upload the file that answers this question. In your Word document (or whatever program you are using), select "File" then "Save As" and select "PDF File". Type in whatever name you want the file to have in the "File name" section. Select which folder you want to save the
file in (I suggest you select "Desktop" so that the file will just
appear write on your desktop home screen. Click
"Save" or "Publish". You should now have your file ready to upload into the
assignment.
Question 8:
Note that you can use the Stat Mode in your calculator to compute the sample mean of this data, as I show in Appendix A of my book. Here is a link where you can download steps for various calculators if you do not know how to use your Stat Mode and do not have my book:
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. I show you how to interpret a P-value in Lesson 2 and provide examples in question 6.
A good rule of thumb when interpreting a P-value is to first stress that you are assuming the null hypothesis is correct (tell them what you therefore believe to be correct according to the hypotheses you have stated), then merely describe the picture you have shaded when visualizing and computing the P-value.
Obviously, you will do all your work in Word (or a similar word processor), do not feel obligated to use fancy math equation writing. You may find on Google or Wikipedia examples of the formulas you need to use which you can copy and paste into your document, but if you find that annoying, just type it out.
For example, you could, if I were computing the z test statistic, where my sample mean is 62, the null hypothesis said the mean is 37, the given population standard deviation is 26, and the sample size n is 14, I could write this:
z = (62 - 37) / (26/ square root(14)) = 25 / 6.94879229 = 3.7417
Note that I put the top in brackets and the bottom in brackets to make it clear what is divided by what. Of course, I have made these numbers up and they have no bearing on your particular question.
For part (a), make sure you have told them the hypotheses, test statistic, and P-value in your answer. Obviously, give them a properly worded conclusion, too. Do not confuse the conclusion you must write with the interpretation of the P-value they require in part (b). Again, for part (c), I show you how to compute a confidence interval with an unusual level of confidence in Lesson 1, question 10. I also show you how to interpret a confidence interval, part (d), in that lesson, question 1 (b).
Once you have answered this question, be sure to save your document as a PDF file as discussed in question 7 above, and upload it to Web Assign.