describe an association between two numerical variables in terms of direction (positive/negative), form (linear/non-linear) and strength (strong/moderate/weak)
3.1.9
use a scatterplot to identify the nature of the relationship between variables
3.1.17
recognise that an observed association between two variables does not necessarily mean that there is a causal relationship between them
3.1.18
identify possible non-causal explanations for an association, including coincidence and confounding due to a common response to another variable, and communicate these explanations in a systematic and concise manner
