Why do I need to do Central Tendency tests?
You need to perform this test if you are looking for a measure of dispersion of your data. Are your values (data) very similar or is the range quite great between your numbers? House prices with an urban area might be very dispersed, however the velocity of a managed, channelised stretch of river might have avery small range as the flow measurements are likely to be very similar.
What do I do first?
Calculate the mean, modal and median values for your numbers. You can find out how to do this in Lenon and Cleves, Fieldwork Techniques and Projects in Geography pages 143-144.
How do I perform the tests?
You can do the test by hand using the instructions in Lenon and Cleves, or or you can cheat a little and use the 'average' function on a scientific calculator or Microsoft Excel.
What do the results mean?
The result will tell you how great the range of your data set is. Measurements of central tendency are usefulfor making large data set more manageable for more accuratesummaries. You may also wish to investigate the 'spread around the mean'. Here you could investigate the standard deviation - Lenon and Cleves, Fieldwork Techniques and Projects in Geography pages 144-145.
How do I use these results in the exam?
You can use your result in a question concerning analysis, conclusions or evaluation.
You may need to say why you did the test, what the outcome was and what this tells you about the data (i.e. is your data set dispersed or not).
The result of your test might support your hypothesis, or it might not - you need to say this.
You need to suggest the other factors that might have influenced the variations in your data, and you need to understand why - to do this you need a good grasp of the under-pinning theory.
Sample Paragraph for Conclusions.
The results of central tendency for total........