Download Stat 31 Handout No

Stat 31 recitation handout
Jan. 29,2002
Bill
Announcements:
1. Homework. The Minitab problem is worth 10 points each, twice that of a textbook
problem. You must do the Minitab problem with computer for credit.
2. Participation points. For one pop quiz, you need to turn in at the lecture something
you have done during the previous computing lab.
Minitab material:
0. How to save and print your work ? Open a Word document. Use copy / cut and
paste. In general, you should avoid printing out the data window.
1. Describing qualitative data (Chapter 3)
Cross tabulation. Click File > Open worksheet  Open the following data.
I:\stat31\Minitab_Data\30Students.MTP
Click Stat > Tables > Cross Tabulation
Bar chart for two categorical variables. Click Graph > Chart  Put ‘Status’ under
X. Click For each, choose Group.  Select CarType in Group variables.  Click
Options. Click cluster. Select CarType in Cluster. OK.
Now do a second chart. Same step as above, but click Total Y to 100% within each X
category.
2. Describing quantitative data (Chapter 4)
Activate the data window.  Click File > Close Worksheet.
Now open following data. I:\stat31\Minitab_Data\GPA.mtp
Stem-and-leaf. Click Graph > Stem-and-Leaf
Histogram. Click Graph > Histogram. Put ‘GPA’ under X.
Dot plots. Click Graph > Dotplot. Or Click Graph > Character Graph > Dotplots.
Descriptive statistics. Use Basic Statistics > Display Descriptive Statistics. , or
Click Enable Commands  type mean C1; type std C1; type median C1.
3. Effect of outlier.
Copy C1 to C2.  Change the first (lowest) GPA from 2.2 to 1 in C2. Now compare
the mean, median and standard deviation for C1 and C2.
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