Hassan Was the Company Plotter

Essay

Hassan was the company plotter. Give him any data set and he could plot a graph that was not only accurate, but also aesthetically pleasing. One afternoon he took some attribute data and plotted it as a p-chart. When Saba, his supervisor, saw the plot he insisted it be discarded and in its place a c-chart should be constructed. Hassan made the c-chart and noticed that when he placed the two charts one on top of the other, the lines created by the data points were exactly the same shape. Has our plotting colleague made a mistake? If not, why should there be these two types of charts when the data generate identical lines?