Minitab Notes for Activity 2

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

Creating the Worksheet

  1. Label four columns as me, and the three personal identifiers from the papers you collected from each student. The example below will assume that they are called A, B, and C.
  2. Enter the values for each person into the appropriate column

Calculating the Differences (Question 3)

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

The original responses are stored in A, B, and C. We're doing to store the squared differences into AA, BB, and CC.

  1. Choose Calc / Calculator
    1. Store your results in AA
    2. The expression is A-me
  2. Repeat the Calc / Calculator command with the second person
    1. Store your results in BB
    2. The expression is B-me
  3. Repeat the Calc / Calculator command with the third person
    1. Store your results in CC
    2. The expression is C-me
  4. Go to Stats / Basic Statistics / Display Descriptive Statistics
    1. Put AA, BB, and CC into the variables box
    2. Click on the statistics button.
      1. Make sure the sum and sum of squares options are checked. You can uncheck the others if you want to.
      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 3.

Summarizing the Data (Question 9)

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. Choose Stat / Basic Statistics / Display Descriptive Statistics
  2. Select the four variables me, A, B, and C by either double clicking each one or by highlighting them all and clicking Select.
  3. Click on Statistics
    1. Make sure the N non-missing, mean, median, variance, and standard deviation are checked
    2. Optionally turn off the other statistics
    3. Click OK
  4. Click OK

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

The variation can be checked by multiplying the variance by the degrees of freedom (df=n-1).

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Last updated August 26, 2008 4:56 PM