# Math Help - histograms

1. ## histograms

I am a bit confused with histograms .

My book says that the area of a rectangle is proportional to the frequency in histograms .

Consider a histogram with equal class widths , is the frequency the height of the rectangle or the area of a rectangle ?

2. Originally Posted by thereddevils
I am a bit confused with histograms .

My book says that the area of a rectangle is proportional to the frequency in histograms .

Consider a histogram with equal class widths , is the frequency the height of the rectangle or the area of a rectangle ?
With equal class-widths the area is proportional to the frequency (area is proportional to class-width times frequency but now the class-widths are constant), so you may as well use the frequency as the vertical axis scale. Note the use of the word proportional, the area is not the frequency but proportional to it.

Personally I don't like non-equal class widths and the area proportional to frequency. I would always use a frequency vertical scale even with variable class-widths except for special circumstances, but you must do what your instructor says rather than what I say of you think is sensible.

CB