Bar graphs are simple to make and to understand. They can show data without implying a relationship. The bars can be horizontal or vertical but should be laid out in the way that the reader expects them. When showing cause and effect data, it is better to use the horizontal axis for the independent variable and the vertical axis for the dependent variable. Bar graphs are the best for presenting data to general audiences.
Pie charts are popular and used often.
However, it is difficult to visually compare the areas in the chart. They are useful to attract attention and when comparing 5 or fewer items. With any of the above types of charts, it is important for the author to present the data accurately and not to try to mislead the reader. Graphs can be distorted in many different ways and journal editors are likely to notice. For example, manipulation of the scale, deletion of data points, or enlargement of data points so that any line would pass through them are all possible abuses.