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Home > Topdrawer > Statistics > Misunderstandings > Difficulties with informal inference

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Difficulties with informal inference

Difficulties with informal inference

Informal inference is about making decisions, often in comparing two data sets or judging the strength of an association. Without formal criteria this process can be difficult.

Informal inference uses evidence collected from samples to make generalisations about underlying populations, acknowledging the degree of uncertainty associated with the generalisation.

In the early years, data collected by students may be treated as a population with no questions asked other than about the data collected.

However, students at year 6 should start to realise that the purpose of statistical investigations is to make claims outside of the data set they collected or are considering.

The following questions may help students to gain this understanding.

  • How much difference in two plots of samples would suggest a difference in the underlying populations?
  • With points on a scatter plot, how close to a straight line do they have to be for a strong association between the two variables?

With comparative box plots, what overlap would indicate that there is no difference in the underlying populations?

Yes

Yes

Name Class Section
Document Is there a difference? Folder 17
Document Meaningful differences Folder 17
Document Differences in heights Folder 17
Document Is there an association? Folder 17
Document Strength of associations Folder 17
Document Judging associations Folder 17
Document Examples of box plots Folder 17
Document Features of box plots Folder 17
Document Interpreting box plots Folder 17
Document Year 9: Compare data displays using mean, median and range to describe and interpret numerical data sets in terms of location (centre) and spread Infobox 3
Document Source Infobox 3