Minitab Notes for Activity 2

Minitab is not needed for this activity, but you may use it to check some of your calculations.

Comparing Student A to You (Questions 4-7)

This is almost easier to do by hand, so use this as a check rather than as the primary method of finding the values.

  1. Label the first column as brand, the second column as me, and the third column as A
  2. Enter the brand names that you shared with student A into the brand column.
  3. Enter your rankings for those brands into the me column
  4. Enter the corresponding rankings for student A into the A column.
  5. Choose Calc / Calculator
    1. Store your results in sqdiff
    2. The expression is (me-A)**2 or you could do (me-A)*(me-A). Note that Minitab uses ** for exponents rather than ^
    3. Click OK
  6. Choose Calc / Column Statistics
    1. Find the sum
    2. The input column is sqdiff
    3. Click OK
    4. The sum that is given on the output screen is the variation

Analyzing Student B (questions 8 - 12)

  1. Label a column is B and enter the ratings for person B into that column.
  2. Go to Stats / Basic Statistics / Display Descriptive Statistics
    1. Select the variable B into the variables box. Leave the "by variables" box empty.
    2. Click on the Statistics button
      1. Check the sum and sum of squares boxes. You may leave other values checked or unchecked, but these are the two important ones for this problem.
      2. Click OK
    3. Click OK

The sum and the sum of squares should match with your totals at the end of the rows in question 8.

Summarizing the Brands (Questions 13-15)

Do this as a check. I want you to find the values asked for by hand as practice for the test.

Minitab does not find the variation for you. Another name for Variation is Sum of Squares, but the Sum of Squares under the Statistics box is the uncorrected sum of squares, which is what you get if you just square the values and add them up, not the value we want which is found by subtracting the mean before squaring the values.

  1. Label two columns with the names of the brands and then enter the ratings for those brands into those columns
  2. Choose Stat / Basic Statistics / Display Descriptive Statistics
    1. Select the two columns representing the brands by either double clicking each one or by highlighting them all and clicking Select.
    2. Click on Statistics
      1. Make sure the N non-missing, mean, median, variance, and standard deviation are checked
      2. You may use the sum and sum of squares to find the variation like you did when evaluating student B.
      3. Optionally turn off the other statistics
      4. Click OK
    3. Click OK

Check the sample size, mean, median, variance, and standard deviation with what you calculated by hand.

An alternative way to find the variation is to use the formula for variance. Since variance = variation / df, you can find the variation by multiplying the variance by the degrees of freedom (df=n-1).