Graphic Methods for Presenting Facts
With few observations it might be desirable to show dots on the chart to actual scale rather than in classes by tens.
Ordinarily a line drawn like the heavy wavy line in Fig. 166 would be so placed that the points on the line would be at the center of gravity for the dots vertically on either side of the line. Here, however, the line is so drawn that there are an equal number of dots on either side of the line, at right angles to it at any point throughout its course.
CORRELATION
Notice that in the upper portion of the chart the hne shifts across the equahty hne, showing that some of the more brilhant girls obtain higher marks in arithmetic than they do in English. The lower portion of the chart shows that the larger number of girls get considerably better marks in English than in arithmetic, and that this is a general condition to be expected. In the case of those girls who do well in both English and arithmetic, there seems to be improved facility in the field of arithmetic.
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