## What is it?

Line graphs are
a common way of presenting data in the form of a picture.

They show the direct relationship, for example, between two quantities
at a glance

## When to use it

- Gathering data
- Analysing data
- Planning and
implementing solutions
- implementing
and testing solutions
- Ensuring continuous
improvement

## What does it achieve?

In the problem solving
process, it is often easier to see results when they are displayed on
a graph than if the results were presented in the form of a table.

Seeing how variables
have changed in the past can give a useful guide as to what can be expected
in the future.

## Summary

- Time series graphs
are used to show relationships between a variable and time
- An index chart
can be used to show percentage comparisons
- A frequency polygon
is used to show frequency distributions
- An Ogive is used
to show cumulative frequency distribution
- A conversion
chart can be used to display the relationship between two variables