Exercise: Comparing peak flow meters

The file meters.sav contains the data from the comparison of two peak expiratory flow (PEF) meters analysed in the lecture for Week 6.

Download the file and read it into SPSS.

Questions

1. Using SPSS, compare the PEF measured using the two instruments using the paired t test. Report the results to a suitable number of decimal places.

Check suggested answer 1.

2. Compute the differences in measured PEF and draw a Normal plot (Q-Q plot). Does the distribution look Normal?

Check suggested answer 2.

3. Compute the average PEF using the two meters and draw a scatter plot of difference against average. Do the differences and averages of the numbers of attacks appear to be related?

Check suggested answer 3.

4. Do you think the data meet the conditions for a paired t test?

Check suggested answer 4.

5. Do you think the PEF measurements themselves follow a Normal distribution?

Check suggested answer 5.

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Last updated: 30 October, 2006.

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