1Bar charts and pictograms
Bar height (or number of icons) shows frequency. Bars don't touch; a pictogram key shows what each icon is worth.
2Line graphs
Used for continuous data over time. Join the points with straight lines to show the trend between readings.
3Pie charts
Angle=total frequencycategory frequency×360∘ 4Scatter graphs and correlation
- Positive correlation: points rise from bottom-left to top-right.
- Negative correlation: points fall from top-left to bottom-right.
- No correlation: no clear pattern.
A line of best fit is a straight line drawn through the middle of the points, used to estimate values.
5Sampling and bias
A population is everyone you could ask; a sample is the smaller group you actually ask. A random sample gives everyone an equal chance of being picked, so it tends to represent the population fairly. A sample chosen for convenience (like only asking friends) is often biased.
💡Correlation is not causation: two things being linked doesn't mean one causes the other.