"A type of error common in both simple and weighted averages is the inclusion of components which have no bearing on or merely distort the summarization. Errors of this kind are frequent in per capita estimates covering the total population." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"An important rule in the drafting of curve charts is that the amount scale should begin at zero. In comparisons of size the omission of the zero base, unless clearly indicated, is likely to give a misleading impression of the relative values and trend." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"Averages and percents should not be averaged. The procedure for obtaining a true average of a number of averages or percents is the same as that for the weighted average. The basic values and com- ponent figures from which the individual averages or percents are derived are totaled. The true average is the quotient of the value total divided by the component total." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"Charts to be shown with a public address should be extremely simple in design. Colors, shading, and curve patterns designating components and categories should be chosen with an eye to strong contrasts. It is essential that the meaning and purpose of the chart be obvious at a glance. If they are not, the attention of the audience is divided between deciphering the chart and listening to what the speaker has to say about it." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"Column charts are bar charts arranged vertically. Their most frequent use is for picturing com- parisons of similar components at different times, while bar charts are generally employed to compare different components at the same time. The column design is particularly effective for the presentation of series which comprise a small number of time periods with few subdivisions of value. It is not well suited for comparisons of several time series nor for those which cover an extended period of time and have many plottings." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"If a chart contains a number of series which vary widely in individual magnitude, optical distortion may result from the necessarily sharp changes in the angle of the curves. The space between steeply rising or falling curves always appears narrower than the vertical distance between the plotting points." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"The grid lines should be lighter than the curves, with the base line somewhat heavier than the others. All vertical lines should be of equal weight, unless the time scale is subdivided in quarters or other time periods, indicated by heavier rules. Very wide base lines, sometimes employed for pictorial effect, distort the graphic impression by making the base line the most prominent feature of the chart." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"The use of two or more amount scales for comparisons of series in which the units are unlike and, therefore, not comparable [...] generally results in an ineffective and confusing presentation which is difficult to understand and to interpret. Comparisons of this nature can be much more clearly shown by reducing the components to a comparable basis as percentages or index numbers." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
"There is probably a higher percentage of errors in the drafting of circle charts than is found in any of the other graphic types, chiefly because of the complicated procedure for calculating the diameters of circles." (Rufus R Lutz, "Graphic Presentation Simplified", 1949)
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