A chart can use true numbers and still mislead. On a bar graph the y-axis usually starts at 0 and is split into equal parts; when it does not, bar heights stop matching the numbers. Pie charts compare parts of a whole and do not show change over time. Every graph needs a title and a source. A claim needs evidence from the whole data, not a hand-picked slice, and often from more than one source. Before sharing a chart, ask who it could help and who it could harm.