**Women more likely to suffer fatigue**

Four sections of the Chance and Data curriculum are represented in this article.

For Data Collection and Sampling, note that the sample in this article was not randomly selected or representative of the country at large. But the report tells us this.The results of the study do not necessarily apply across the nation because the 206 women and 67 men were members of the ME/CFS Society of New South Wales and a northern Sydney CFS youth support group rather than a randomly selected slice of the general populationWe now have the option of disregarding the results if we choose or of using caution in applying the conclusions to other groups. This is a case of excellent reporting.

For Chance and Basic Probability, notice the reference in the first sentence to women being three times more likely than men to suffer CFS. This statement can be represented asPr (CFS | female) = 3 Pr (CFS | male)

[Here Pr (A | B) is the probability of event A occurring given the occurrence of event B]. Note, however that the data presented in the paragraph above suggest that the conditional statement should be written in a different order: on the condition that you are in the CFS group, Pr(female) = 206/273 and Pr(male) = 67/273.

For Data Reduction, notice the use of the averages, which given the decimal form (4.7 years, 1.8 years and 25.8 visits to a doctor per year) must be arithmetic means. Also percentages are presented (30% inapprpriately referred to a psychiatrist), as is a range of values (150,000 to 100,000 people).

For Inference, this article could be used to discuss what conclusions can be drawn from the sample described or from other statistics presented in the article. Given the uneven represenation of males and females in the sample, some concerns should be expressed about how much confidence can be placed in the claims about the averages in the second paragraph. Further, more sophisticated statistical information would be needed to make confident judgements.

Where to next?Student Questions for this article

Newspaper article

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