Variability is a theme within reasoning about data. Links to relevant activities and resources are on the right hand side of this page.
Variability in data may be explained or modelled as the effect of identifiable factors. Alternatively, variability may be regarded as random noise or error, by which it is meant that the variability is not ascribed to any specific factor.
How might naïve students make judgements of what should be regarded as variability due to a main effect and what should not? Statisticians have developed methods for making such judgements, but research is interested in how students might make such judgements, and how teachers or resources might support more sensitive or sophisticated informal inferential reasoning about underlying trends.