# Statistical Diagrams

Students learn how to plot and interpret various statistical diagrams ranging from pictograms and barcharts to frequency polygons and time series.  Throughout the unit emphasis is place on interpreting the diagrams as much as it is plotting them.

This unit takes place in Year 9 Term 1 and is followed by calculating statistical measures such as averages and range.

##### Prerequisite Knowledge
• solve comparison, sum and difference problems using information presented in a line graph
• complete, read and interpret information in tables, including timetables.
##### Success Criteria

interpret and construct

• frequency tables
• bar charts
• pie charts
• pictograms
• pie charts

for categorical data.

• interpret and construct
• vertical line charts for ungrouped discrete numerical data
• tables and line graphs for time series data

and know their appropriate use.

##### Key Concepts
• Frequency tables must not have overlapping categories
• Diagrams must not imply bias (e.g., equal width bar charts0
• Pictograms need to use suitable symbols to illustrate fractional amounts
• Students need to spend time interpreting the diagrams as well as creating them.
##### Common Misconceptions
• Bar charts are often drawn with unequal width bars.
• Students often use nonlinear scales for bar and line graphs.
• The frequency is often incorrectly taken as the angle when drawing pie charts.
• Diagrams are often drawn without the correct labels and missing titl

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