Expressiveness and Effectiveness

Learn about the expressiveness and effectiveness principles of visualising data!

expressiveness principle

the encoding should express all of, and only, the information in the dataset attributes

expressiveness 1

show ordered data in a way such that our system perceives an order

expressiveness 2

show categorical data in a way that does not suggest any ordering

effectiveness principle

the most important data attributes should be encoded with the most effective visual variables, in order to be most noticeable

accuracy

how accurate is our perception of a visual variable?

discriminability

how many distinctions are possible?

discriminability notes

colour hue is limited to 7, position is much more versatile

separability

how does the visual variable interact with others?

popout and grouping (selective)

how easily can we identify items that stand out?

popout and grouping (selective) note

strong variables are position, colour and shape

popout and grouping (associative)

how easily can we see if items are similar and belong to the same group?

popout and grouping (associative) note

strongest variable is position