Stat 2000: Tips for Assignment 5
Published: Sun, 01/29/12
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Did you miss my Tips on How to Do Well in this Course? Click here
Did you miss my Tips for Assignment 4? Click here
If you are taking the course by classroom lecture (Sections A01, A02, etc.), click here for my tips for your Assignment 5.
Study Lesson 5 in my study book to prepare for this assignment.
For Question 1, note that ni simply means they want you to tell them the values of n1, n2, etc.. Simply tell them n1 = #, n2 = #, etc. (replacing # with the appropriate numerical value). Depending on the specific question you were given, some of you will have the same values for all of n1, n2, etc., whereas, for others, the values of n1, n2, etc. will be different. Of course, N and I are as I describe in Lesson 5.
For Question 2, you should certainly
use the stat mode in your calculator to compute the means and standard
deviations (which will, of course, enable you to know the variances),
then do the rest of the problem by hand using the formulas for SSG, SSE,
MSG, MSE, and F. Make sure you have memorized those formulas (and the
formula for the overall mean or grand mean). There is almost certainly
going to be a question or two on the exam that will check to see if you
know these formulas (although it is rare to see an exam question that
makes you do an entire ANOVA by hand). It is common that an exam will
make you compute MSG or MSE by hand having been given the sample means
and standard deviations. Note, throughout the question they tell you to do "second - first", so make sure you do. That makes their hypotheses confusing. I assume they mean by μ1 the mean of the first coinage, but, then again, it doesn't really matter.
Here is how to do the JMP part of Question 3:
It is done the same way you did the JMP in the
previous assignment. Open a New Data Table and type the data in
manually in this manner (don't bother pasting and stacking, it is not
worth the effort): Name your first column "Silver" or something like
that, and type all the silver contents down that column. Which is to
say, type in the numbers from the First coinage down the column, then
continue to type all the numbers from the Second coinage, and finally
continue to type all the numbers for the Third coinage. Double-click at
the top to the right of the "Silver" column heading to create a new
column and name it something like "Coinage". Down that column
type "First" repeatedly down that column in all the rows that have the
data for the First coinage. Then type "Second" repeatedly down the
column in the rows that have data for the Second coinage. Finally, type
"Third" for the rest of the column. You may want to type the phrase
once and then copy and paste it down the rest of the relevant rows to
ensure there are no typos. Once you have done that, double-click the
"Coinage" column heading and confirm that the Data Type is Character and
the Modeling Type is Nominal and click OK.
Select Analyze, then Fit Y
By X. Highlight the numeric column "Silver" and click the Y, Response
button. Highlight the character column "Coinage" and click the X,
Factor button. Click OK.
You should now see a graph
with three vertical arrays of dots showing the silver content for the
three different coinages separately. (If you do not see a graph like this, but, for example, see a Mosaic Plot, that means you did not label the Data Type and Modeling Type properly. Go back to your data table, double-click each column and make sure the Data Type and Modeling Type for each column is as I indicate above.) Click the red triangle and select
"Means and Std Dev" to get a summary of the means and standard
deviations of the three samples. Click the red triangle again and
select "Means/Anova/Pooled t" to get the output you need.
By the way, be sure to
study my questions 5 and 6 in Lesson 5 thoroughly to better understand
what they are getting at in part (d).
In Question 4
the applet is pretty straightforward to learn from. Note that the
pooled standard error is essentially MSE. Remember, F = MSG/MSE and
think about what affects the value of MSG and MSE and how those two
values affect the value of F. The applet pretty well teaches you what
happens. Messing with one part changes MSG, messing with the other part
changes MSE.
Do the JMP in Question 5
just like I showed you what to do in Question 3 above. Here at least
you can copy and paste the data into JMP. Be sure to paste it into JMP
by selecting Edit, then, while holding down the Shift key, select Paste
in order to paste the column headings properly (or, after you have
copied the data, select "Edit" then "Paste with Column Names"). Note,
double-click the "bfed" column and confirm that its Data Type is
Character and Modeling Type is Nominal; double-click the "energy" column
and confirm that its Data Type is Numeric and Modeling Type is
Continuous. Always make the numeric column Y and the character column X
when you select Fit Y By X.
Re-read my section on the P-value in Lesson 2 of my book if you still are not sure how to interpret a P-value.