Minitab Instructions for Chapter 9 Technology Exercise

Correlation Between Exam 1 and Exam 4 (Question 1)

Entering the Data into Minitab

  1. Create two columns, one called exam1 and one called exam4.
  2. Enter the data into the two columns

Summarize the Variables (part a)

You really ought to know how to do this by now.

  1. Choose Stat / Basic Statistics / Display Descriptive Statistics
  2. Describe exam1 and exam4
  3. Click OK

Scatterplot (part b)

  1. Choose Graph / Scatterplot / with Regression
  2. The y-variable is exam4 and the x-variable is exam1.
  3. Click OK
  4. Copy and paste the graph into Word

Correlation Coefficient and P-value (parts e & f)

  1. Choose Stat / Basic Statistics / Correlation
  2. Select both exam1 and exam4 for the variables

Regression Equation (part j)

If you said that you should use the equation given by the computer to make predictions, then do the following. Otherwise the regression equation is that the predicted exam4 value equals the mean of the exam4 variable.

  1. Choose Stat / Regression / Regression
  2. The response variable is exam4
  3. The predictor variable is exam1
  4. Click OK
  5. The top of this section of output (you may need to scroll up to find it) contains the regression equation. Copy and paste the regression equation into Word.

M&M Colors (Question 2)

Finding the claimed proportions

  1. Go to the M&M website at http://www.mms.com/
  2. Click on About M&Ms
  3. Choose Products
  4. Choose Peanut M&Ms
  5. The claimed percentages are given, but the web page is not accessible, so if you're color blind, have your partner look at the page and send a note to M&M Mars letting them know that their page isn't accessible.

Finding the critical value (part d)

  1. Choose Calc / Probability Distributions / Chi-Square
    1. Select Inverse cumulative probability
    2. The degrees of freedom is one less than the number of categories
    3. The input constant is 0.95, the area to the left of the critical value (this is a right tail test with α = 0.05, but Minitab needs the area to the left).
    4. Click OK
  2. The critical value is what Minitab calls X

Finding the test statistic and p-value (parts e & f)

  1. Label the first column as Color and enter the names of the colors
  2. Label the next two columns in as Observed and Claimed
  3. In the Observed column, enter the observed frequencies from Classroom Activity 7. Be sure you use the data for your section.
  4. In the Claimed column, enter the percents as claimed from M&Ms. You may enter them as percents or proportions, but do not actually put the % sign in there.
  5. Choose Stats / Tables / Chi-Square Goodness-of-Fit Test (One Variable)
    1. The observed counts are in the Observed column.
    2. The category names are in the Color columns
    3. You are testing proportions specified by historical counts. These counts are in the claimed column. (If you put in proportions instead of percents, you can still use this or you can use "specific proportions" and the output will be a little less cluttered).
    4. Click on Graphs and turn all graphs off.
    5. Click OK

The results have a Chi-Sq, which is your test statistic and a P-value, which is your p-value. The "expected" column contains the expected frequencies.

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Last updated November 13, 2005 9:07 PM