In Fig. 152 the curves show the time required to answer calls in different cities, while Fig. 153 shows a comparison of answering times in different classes of service. Notice that in each of these two charts it seems that two seconds is about the minimum which can be expected in answering telephone calls with the existing types of equipment. Fig. 153 certainly gives in excellent manner the comparison between the answering times for different classes of service. It would be very difficult to convey the complex information contained

in Fig. 153 by using tabulated figures only. Tabu-

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Telephone Service in Wisconsin Prompinei5 of Operators in Answering Calls Curves Shotting Conditions inCities of Various 5ize^ A. Average Speed in all Cities over 10,000 CU3 Calls ~ S - ... ■ of WOO to 10,000 634 ■• C ■ .... Under i,0O0[ £76 -

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lated figures would take up as much space as the chart and they would be less intelligible to any person who knows even the rudiments of reading graphic presentations.

In Fig. 154 an attempt was made to apply cumulative freciuency curves to a comparison of wage rates in different sections of the United States. The chart, however, is likely to be very misleading, as it has been plotted by methods which are not in accordance with usual practice. The variables have been reversed, and the independent variable has incorrectly been made the vertical scale. Besides that, the vertical scale reads downward instead of upward. In all kinds of curve plotting it is common to have the two scales begin with zero at the lower left-hand corner of the chart. Here the two scales begin the zeros at the upper left-hand corner of the chart.