We thought long and hard about the teaching of histograms within a Business Statistics course. Another exampleĪll it takes is some relabelling and the meaning is clear.
An Excel column chart is designed to be a value graph for nominal data, and it is being pressed into service in an unnatural way. That is because the only way you can get the number and the tick mark to line up, is to move the tick mark to the centre. Intuitive!Ī Google search on the word histogram shows most of the histograms with the tick marks at the boundaries, and quite a few using the Excel work around shown above. If you went to school last century and learnt to draw them by hand, you would put the boundary number between the bins on the tick mark on the graph that was the boundary between the bins. Graphs exist in order to communicate, not confuse.Ī histogram always has “bins” which cover a range of values. This is too many assumptions for any graph. That is two too many assumptions for students in an exam. I make this assumption because I know that is what Excel does. To get this answer I assume that the lambs are weighed to a precision of one decimal place, and the numbers under the graph are the inclusive upper bounds for the area above.
I suspect the desired answer is one out of 32. The labelling of the horizontal axis renders this question unanswerable. The first question asks: “What proportion of the lambs weighs less than 1.25 kg?” The results are shown on the histogram above.” She records the weights of 32 lambs born on her farm. The introduction says: “Ali has a farm in Southland.
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