Measures of Central Tendency (Mean, Median, Mode)
Mean, median, and mode summarise data using a single representative value, each useful in different situations depending on data characteris
Core concept
For grouped data, mean is calculated using the formula involving class midpoints and frequencies, often using the direct or step-deviation method.
How it works
Median for grouped data is found using the formula: Median = l + [(n/2 - cf)/f] × h, where l is the lower boundary of the median class.
Why it matters
Mode for grouped data uses the formula: Mode = l + [(f₁-f₀)/(2f₁-f₀-f₂)] × h, based on the frequencies of the modal class and its neighbours.
Key detail
Understanding these measures for both ungrouped and grouped data helps us analyse and summarise different types of statistical data.
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Quick notes
• Grouped data mean uses class midpoints and frequencies.
• Methods: direct or step-deviation method.
• Median formula: l + [(n/2-cf)/f] × h.
• l is the lower boundary of the median class.
• Mode formula: l + [(f₁-f₀)/(2f₁-f₀-f₂)] × h.
• This uses modal class and neighbouring frequencies.
• These work for grouped data.
• Understanding all three helps comprehensive data analysis.