# Statistical Measures

Students learn how to calculate averages with discrete and continuous data from stem and leaf diagrams and frequency tables..  They use these to compare distributions and analyse sets of data.

This unit takes place in Year 9 Term 1 and is followed by representing data using diagrams.

##### Revision Lessons

Problem Solving with Averages

##### Prerequisite Knowledge
• Interpret and present discrete and continuous data using appropriate graphical methods, including bar charts and time graphs.
• Solve comparison, sum and difference problems using information presented in bar charts, pictograms, tables and other graphs.
##### Success Criteria
• Interpret, analyse and compare the distributions of data sets from univariate empirical distributions through:
• Appropriate graphical representation involving discrete, continuous and grouped data
• Appropriate measures of central tendency (median, mean, mode and modal class) and spread
• Construct and interpret stem and leaf diagrams
• Apply statistics to describe a population
##### Key Concepts
• A frequency table is used when the sample size increases beyond simple calculations being possible from a list.
• The median average of a class width is used as the mid-pint when calculating the mean from grouped data.
##### Common Misconceptions
• Students often find it difficult to calculate the median average from data presented in a frequency table.
• When sorting continuous data into a grouped data table students often struggle to fully understand the inequality notation.

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