General Maths – Foolproof Explanations
🎯 WHY choose different graph types?
📊 Bar chart - WHY?
Use when: categorical data
Why:
Categories are separate groups (not numerical order)
We want to compare sizes of groups
Gaps show categories are distinct
✅ Best for: popularity, preferences, types
❌ Not good for: continuous numerical data
Exam wording:
A bar chart is appropriate because the variable is categorical and the categories are distinct.
📈 Histogram - WHY?
Use when: numerical data (especially continuous)
Why:
Data has a natural numerical order
Shows the shape of the distribution
Bars touch because values flow continuously
Helps identify skew, clusters, spread
✅ Best for: heights, times, money
❌ Not for: favourite colour, brand names
Exam wording:
A histogram is appropriate because the data are numerical and continuous, so the distribution
shape is important.
🔵 Dot plot / stem plot - WHY?
🎯 WHY choose different graph types?
📊 Bar chart - WHY?
Use when: categorical data
Why:
Categories are separate groups (not numerical order)
We want to compare sizes of groups
Gaps show categories are distinct
✅ Best for: popularity, preferences, types
❌ Not good for: continuous numerical data
Exam wording:
A bar chart is appropriate because the variable is categorical and the categories are distinct.
📈 Histogram - WHY?
Use when: numerical data (especially continuous)
Why:
Data has a natural numerical order
Shows the shape of the distribution
Bars touch because values flow continuously
Helps identify skew, clusters, spread
✅ Best for: heights, times, money
❌ Not for: favourite colour, brand names
Exam wording:
A histogram is appropriate because the data are numerical and continuous, so the distribution
shape is important.
🔵 Dot plot / stem plot - WHY?
