MINI-USER’S GUIDE FOR DDXLHOFFMANSpring, 2005

  1. Using a web browser (probably Netscape or maybe IE) go to my website at
  2. Click on “Information on Courses”
  3. Click on “Math2200”
  4. Click on (you could also go there directly)
  5. Click on “Datasets”
  6. Look down the first few columns and find Chapter 6, Problem 13 – the Olympics data. Look for the Excel column and double click on that xls file. Note that the XL spreadsheet program should pop up.
  7. Click on Column A and highlight the column for activity.
  8. Go up to the top toolbar and click on “DDXL” and click your cursor on “Charts and Plots”
  9. Click on “Function Type” and select “Histogram” (for example).
  10. Notice that the “Names and Columns” contains your variable name of Time. Click on “Time” and then on the arrow to move it to the variable box.
  11. Now click “OK”.
  12. You now get a Data Desk window. Answer queries 1&2&3 below.
  13. X out of the Data Desk window at the top right and click “Don’t Save”
  14. Open up a new XL window by clicking on “File” the top toolbar on the left and selecting “New” and clicking on “Workbook” and “OK”
  15. We will now enter some age and miles data that we have seen in class. In the first row of Column A type the word “age” and Column B should contain the label “miles”. Enter the following data in columns A : 1, 6, 9, 7, 14, 15, 6, 2 and in column B: 10, 117, 150, 89, 150, 98, 35, 26 .
  16. Again, click (and drag) on columns A and B to highlight them.
  17. Go up to the top toolbar and click on “DDXL” and click your cursor on “Regression”
  18. Click on “Function Type” and select “Correlation”
  19. Notice that the “Names and Columns” contains your variable names of Age and Miles. Click on “Age” and then on the arrow to move it to x-axis and on “Miles” and then the arrow to move it to the y-axis variable box.
  20. Now click “OK”
  21. You now get a Data Desk window. Answer query 4 below.
  22. X out of the Data Desk window at the top right and click “Don’t Save”
  23. Again, click (and drag) on columns A and B to highlight them.
  24. Go up to the top toolbar and click on “DDXL” and click your cursor on “Regression”
  25. Click on “Function Type” and select “Simple”
  26. Notice that the “Names and Columns” contains your variable names of Age and Miles. Click on “Age” and then on the arrow to move it to Explanatory and on “Miles” and then the arrow to move it to the Response variable box.
  27. Now click “OK”
  28. You now get a Data Desk window. Answer queriy 5 below.
  29. X out of the Data Desk window at the top right and click “Don’t Save”
  30. Repeat steps 14 – 29 above but use this data for column A: 2, 3, 4, 5, 9 and for column B: 105, 81, 68, 47, 29
  31. Answer the query 6 below and then go on to answer query 7.

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Name: ______

1. What is the mean ski time? ______2. What is the standard deviation ski time? ______

3. Is the distribution of ski times skewed: Left Right Symmetric

4. For the age and miles data, what is r? 5. Write out the regression line.

6. Find r and the regression line for the new data in step 30 above.

7. Enter your data collected yesterday on car age (X) and car miles (Y) into an EXCEL spreadsheet and conduct a regression analysis on the data:

a)Use DDXL to write out your formula for the regression line

b)Find the correlation coefficient r from the DDXL.

c)Recall that in your hand calculations you guessed at the standard deviation; but still was your hand calculation of r very close to the exact value calculated by DDXL?