Why are the bars on the histogram touching and not separated?

Answer 1

Your observation is correct for a histogram that involves numbers. The width of each bar indicates the span of that group -- the left-hand edge is the lowest value in the group and the right-hand edge is the highest. A histogram indicates how many counts that fall within the specific boundaries of a bar as indicated by the bar width (the bar height indicates the count). For example, if I decide that the bar width should be one unit each, I construct the histogram with bars one unit wide. However, when the count is zero for some intervals, then there will be a gap of one unit wide. I probably increase my bar width to avoid gaps, so that all bars are touching. Under certain abnormal circumstances will I see gaps.

Now the story is different for bar graphs. They are normally made of categories (for example, apples, Pears, and Oranges). In this case, the gap between bars is fine.

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