Statistics & Probability
Roughly a third of the WST. Reading tables, graphs and basic statistical summaries — the same skills you'll use reading incident data, response time logs, and operational reports.
Reading Tables and Graphs
ACSF: Extracts, interprets and comprehends statistical data in tables, graphs and charts in everyday and work contexts
Reading and interpreting data from tables, bar graphs, line graphs, pie charts and pictographs. Identifying trends in incident data, response time logs, equipment performance reports.
Key skills
Common mistake: Misreading the scale on a graph axis. Always check what each grid line represents before reading off a value.
Mean, Median, Mode and Range
ACSF: Calculates and interprets measures of central tendency (mean, median, mode) and spread (range) in everyday contexts
Calculating mean, median, mode and range. Choosing the most appropriate measure of centre for a given context. Effect of outliers — relevant when reading response time or incident data.
Key skills
Common mistake: Finding the median without sorting the data first. Always arrange values in order before finding the middle.
Stem-and-Leaf Plots
ACSF: Reads and interprets stem-and-leaf plots to identify and compare distributions
Reading and constructing stem-and-leaf plots. Finding median and mode from a stem-and-leaf plot. Back-to-back plots for comparing two data sets (e.g. station A vs station B, day shift vs night shift).
Key skills
Common mistake: In a back-to-back plot, the left side reads right-to-left. 3 | 2 | 5 8 means 23 on the left and 25, 28 on the right.
Probability
ACSF: Calculates and interprets probability of simple and complementary events in everyday contexts
Probability as a fraction, decimal or percentage. Complementary events. Simple probability from equally likely outcomes. Expected frequency over a number of trials.
Key skills
Common mistake: Forgetting that P(A) + P(not A) = 1. If P(rain) = 0.3, then P(no rain) = 0.7.
Frequency Tables and Histograms
ACSF: Constructs and interprets frequency tables and histograms to represent and analyse data distributions
Reading and constructing frequency tables. Interpreting histograms (no gaps between bars). Relative frequency as a proportion or percentage.
Key skills
Common mistake: Confusing bar graphs (categorical data, gaps between bars) with histograms (numerical data, no gaps). WST questions often test this distinction.
Scatter Plots
ACSF: Interprets scatter plots to identify and describe associations between two numerical variables
Reading and interpreting scatter plots. Describing the direction (positive/negative) and strength (strong/weak/none) of correlation between two variables.
Key skills
Common mistake: Correlation does not imply causation. Two variables can be strongly correlated without one causing the other.
Interpreting Statistical Reports
ACSF: Interprets and evaluates statistical information in media reports, including claims about data and graphical representations
Critically evaluating statistical claims in reports — common in operational briefings, incident summaries, and equipment performance reviews. Identifying misleading graphs (truncated axes, unequal intervals).
Key skills
Common mistake: Accepting a graph at face value without checking the axis scale. A y-axis starting at 90 makes a 2% difference look enormous.
Ready to test yourself?
Take the free 13-question diagnostic — see exactly where you stand across the WST numeracy strands. Or sit a full practice paper free, no sign-up needed.