Nayland College - Mathematics
Inference HOME | Achievement Objectives | Overview | Statistical Cycle
Discussion of Sample Displays
When describing dot plots: discuss symmetry, skew, outliers, gaps, clusters
Box and whisker: Summary statistics, symmetry, skew
It there are sub groups or a second variable using different colours to show this, and discuss as well.
“In my sample...”
The discussion needs be in context at all levels. The context includes the variable, for example height, numerical values and associated units and the population groups.
Distribution Sample Shapes.pdf (link to Census at schools)
Symmetry - Is the data symmetrical either side of the median? Or is one side more spread out?
Skew - Data spreading right is right skewed
Any data more than 1.5 ‘boxes’ above UQ is an outlier. Data more than 3 ‘boxes’ above UQ is extreme (see later notes)
Clusters - A bunching of data in one region
When describing Box and whisker: Summary statistics, centrality, spread, symmetry, skew, tail length
Summary statistics (Review) – do not discuss Max or Min (irrelevant)
Discuss the ‘middle 50%’ ie the ‘box’ and median If comparing samples discuss overlap and shift (eg distance between medians)
Show groups or a second variable using a different group colour. Discuss these groupings
And for merit things like: ‘I notice ... I expected ... I was surprised that...’