When information is presented in the form of a bar graph or time- series graph, you could get more exact values if all the data were just listed out in table form. Then why not always do that. Why bother with graphs?
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Step 1:
Graphs are essentially a visual display of quantitative information along two axes. Visuals are used as a way for our brains to quickly understand information, which is a powerful tool if used correctly. Graphs can show a large amount of data quickly in a way that is easy to process, without distracting people with a bunch of numbers.