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Chapter 7 - Analysing the Data Part IV - Analysis of Variance Chapter 1 - Behavioural Science and research Chapter 2 - Research Design Chapter 3 - Collecting the Data Chapter 4 - Analysing the Data Part I - Descriptive Statistics Chapter 5 - Analysing the Data Part II - Inferential Statistics Chapter 6 - Analysing the Data Part III - Common Statistical Tests The Scientific Approach The Research Process Variables Confounds The Logic of Cause and Effect Research Hypothesis and Predicition Readings and Links

Chapter 1
Behavioural Science and Research


The Logic of Cause and Effect

In the previous little study, if everything went according to plan we were interested in being able to claim that the new method for learning the alphabet caused an improvement in the acquisition of that skill. Why else would we go to so much trouble? If we did find evidence that singing caused an improvement compared to pronouncing then we would adopt that into the way we do things expecting that the next time we did it we would again see an improvement.

So, if we assume that the identification of cause and effect relationships is the fundamental aim of science, we need to establish the conditions under which this is most likely to be inferred. Three conditions need to be established for a cause and effect relationship between A and B to be established.

  • A must occur before B
  • Variations in A must covary with variations in B
  • All confounding variables must be controlled

For example, if you hypothesised that it was wattle flowers that were making you sneeze, you would need to

  • notice that you sneezed after you were near the wattle
  • notice that you sneezed after you were near the wattle and that you did not sneeze when you were not near the wattle
  • notice that you did not sneeze after you had been near other flowering plants

To be really convinced that it was the wattle, the above little experiment would need to be repeated a number of times. If the three conditions maintained each time repeated the experiment you would have isolated the real cause of your sneezing from.




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