Minitab Notes for Activity 2

Creating the Worksheet

  1. Label the columns with the name of the person
  2. Enter the distances for the first person under his/her name and the distances for the second person under his/her name.
  3. Save the file

Summarizing the Data (Question 2)

  1. Go to Stat / Basic Statistics / Display Descriptive Statistics
  2. Select both columns for the variables
  3. Click OK

Comparing Two Standard Deviations (Question 9)

We will actually compare two variances instead of two standard deviations. Recall that the variance is just the square of the standard deviation.

There are two possible tests for checking whether the standard deviations are equal. The first is called the F-Test and you should use these results if the samples come from populations that are normally distributed. The second is called Levene's test and should be used if the samples come from populations that are not normally distributed. So, the first thing to do is see whether or not the populations are normally distributed.

  1. Go to Stat / Basic Statistics / Normality Test
  2. Select the first person for the variable
  3. Click OK
  4. Look at the normal probability plot to determine normality
  5. Repeat steps 1-4 with the second person and determine normality for them.

Okay, now we're ready to do the check for equality of the variances.

  1. Go to Stat / Basic Statistics / 2 Variances ...
  2. Click on the Samples in different columns radio button
  3. Select your data for the first variable
  4. Select your partner's data for the second variable
  5. Click OK
  6. You can close the graph, you won't need it for this problem although it gives you a nice graphical representation of the variances.
  7. Look at the p-value for the appropriate test depending on whether the samples were from normal populations.

Comparing Two Means (Question 10)

  1. Go to Stat / Basic Statistics / 2 Sample t
  2. Click on the Samples in different columns radio box
  3. Select your data for the first variable
  4. Select your partner's data for the second variable
  5. If you decided in question 9 that your results were not unusual, then check the Equal variances assumed box. If you decided in question 9 that your results were unusual, then do not check the Equal variances assumed box.
  6. Click OK

Comparing Two Medians (Question 11)

  1. Go to Stat / Nonparametrics / Mann-Whitney
  2. Select your data for the first sample
  3. Select your partner's data for the second sample
  4. Click OK
  5. The output will say Test of ETA1 = ETA2 ... is significant at 0.####. That number is the p-value.

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Last updated January 7, 2003 8:21 PM