A bar chart is judged by the length of the bar ... to large values and multiplicative factors. The next example just describes rates of change. Suppose we had one widget in 1999 and doubled ...

A line graph shows how data changes over time. For example, how the volume of traffic changes over a day so you can see the busiest times. A bar chart is best for comparing groups of data.

The maximum stock level is the largest amount of stock a business can store on site. In the bar graph example, it is 500 items of stock. The minimum stock level is also known as buffer stock.