These curves start at the lower left-hand portion of the field and trend upward, showing that they are plotted on a "less than" basis. Curve A shows a smaller time required to answer calls than Curves B or C, yet the actual position of Curve A on the chart is higher than either curves B or C. If cumulative frequency curves are plotted on a "more than" basis the position of several curves on a chart is relatively such that the reader is not confused so much as when curves are plotted on a "less than" basis

FREQUENCY CURVES

words "more than", with an arrow, had been placed at the lower left-hand corner of the chart. In Fig. 155 a little study will show the advantages of plotting curves on a "more than" basis. The reader can see at a glance from this illustration that the wages for the western States are very much higher than the wages in the south Atlantic States. The position of the curves one above the other would lead the reader at once to think of the upper curves as showing higher wages. Here the upper curves do indicate the higher wages, but they would not do so if they were plotted on a "less than" basis instead of on a "more than" basis. Though it may cause some confusion at first, it seems desirable as a general rule that cumulative frecpency curves should be plotted on a "more than" basis rather than on a "less than" basis.