Mathematics·Statistics and probability · NSSCO 12.2
Averages & measures of spread
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Averages are the friendly little numbers that sum up a whole pile of data in one go. In this lesson we meet the mean, the median, the mode and the range, and find all four from a simple list step by step. We watch how a single outlier can drag the mean around, learn which average to trust, then work from a frequency table and from a grouped table where we estimate the mean and name the modal class. We finish by comparing two data sets fairly — using both an average and the range.
What you'll learn in this lesson
By the end you should be able to (NSSCO Mathematics 12.2):
- Find the mean, median, mode and range of a list of discrete data
- Calculate the mean, median and mode from a frequency table
- Estimate the mean of grouped data using class midpoints
- Identify the modal class from a grouped frequency distribution
- Compare two data sets using an average together with the range
- Choose the most appropriate average, and describe the effect of an outlier
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