💡 What is a Frequency Table?
Instead of listing every single value, we count how many times each value appears — that's the frequency.
Then we multiply: value × frequency = fx. Add up all the fx values, divide by total frequency → mean.
It's the same calculation as before, just organised more efficiently for large datasets.
Then we multiply: value × frequency = fx. Add up all the fx values, divide by total frequency → mean.
It's the same calculation as before, just organised more efficiently for large datasets.
📋 Build the Frequency Table
Add values that appear in your dataset. Enter the frequency (how many students got each value).
Value:
Frequency:
No rows yet — add values above, or import from Lesson 1
🔢 Averages from the Table
MEAN
—
Σ(fx) ÷ Σf
MEDIAN
—
Middle position in cumulative f
MODE
—
Highest frequency
RANGE
—
Max − Min
🚨 Outlier Alert!
💬 Discussion Prompts
Why do we multiply value × frequency? What would go wrong if we just added up all the values in the x column?
The fx column total is Σ(fx) — why do we divide by Σf (total frequency) and not by the number of rows?
If you add a Brainrot character with an extreme value, which average changes the most — mean, median or mode?
Compare the mean here to your mean from Lesson 1. Are they the same? They should be — why?
💡 What is a Grouped Frequency Table?
When data is spread across many values, we group them into class intervals (e.g. 6–8 hours).
We can no longer find the exact mean — we estimate it using the midpoint of each group.
We also talk about the modal class (most frequent group) and the median class (which group contains the middle value).
Grouping loses information — that's why the mean is only an estimate.
We can no longer find the exact mean — we estimate it using the midpoint of each group.
We also talk about the modal class (most frequent group) and the median class (which group contains the middle value).
Grouping loses information — that's why the mean is only an estimate.
📦 Grouped Frequency Table
Group width:
Change width and click Regroup to see different groupings
Import data or build a frequency table first, then click Regroup
🔢 Estimated Averages
EST. MEAN
—
Σ(fm) ÷ Σf using midpoints
MODAL CLASS
—
Group with highest frequency
MEDIAN CLASS
—
Group containing middle value
EST. RANGE
—
Width of outer groups
🔍 Lesson 1 vs Estimated Mean
💬 Discussion Prompts
Why do we use the midpoint of each group? What assumption are we making?
Compare the estimated mean to the exact mean from the frequency table. How close are they? Why aren't they identical?
Change the group width. Does the estimated mean change? Why does grouping change the estimate?
Which is more useful to a scientist — the exact mean or the grouped estimated mean? When would you choose each?
Can you find the exact mode from a grouped table? Why is it called "modal class" and not just "mode"?