"Admittedly a chart is primarily a picture, and for presentation purposes should be treated as such; but in most charts it is desirable to be able to read the approximate magnitudes by reference to the scales. Such reference is almost out of the question without some rulings to guide the eye. Second, the picture itself may be misleading without enough rulings to keep the eye 'honest'. Although sight is the most reliable of our senses for measuring (and most other) purposes, the unaided eye is easily deceived; and there are numerous optical illusions to prove it. A third reason, not vital, but still of some importance, is that charts without rulings may appear weak and empty and may lack the structural unity desirable in any illustration." (Kenneth W Haemer, "Hold That Line. A Plea for the Preservation of Chart Scale Ruling", The American Statistician Vol. 1 (1) 1947)
"If perspective must be used - and it does have proven
attraction value - it should be used with restraint. A slight rather than a
sharp convergence provides definite novelty with negligible distortion. Also, perspective
should be used consistently: that is, the same perspective for all charts in
the presentation. Any resultant overstatement or understatement of the data
will thus be uniform throughout. In any event, horizontal scale rulings should
be used to enable the reader to check the visual impression, and to evaluate
the plottings." (Kenneth W. Haemer, "The Perils of Perspective", The American
Statistician Vol. 1 (3) 1947),
"To the question "how many rulings is the 'right' number?" there is unfortunately no easy answer. Charts designed to perform the work of a large amount of tabular data, being primarily tabular in purpose, obviously require closer rulings than charts designed primarily to present a picture. But even within these two groups the decision may be influenced by the precise purpose of the chart, its size and shape, the nature of the data, the degree of reading accuracy needed, and to some extent, by the style of the medium in which the chart appears." (Kenneth W Haemer, "Hold That Line. A Plea for the Preservation of Chart Scale Ruling", The American Statistician Vol. 1 (1) 1947)
"[….] double-scale charts are likely to be misleading unless the two zero values coincide (either on or off the chart). To insure an accurate comparison of growth the scale intervals should be so chosen that both curves meet at some point. This treatment produces the effect of percentage relatives or simple index numbers with the point of juncture serving as the base point. The principal advantage of this form of presentation is that it is a short-cut method of comparing the relative change of two or more series without computation. It is especially useful for bringing together series that either vary widely in magnitude or are measured in different units and hence cannot be compared conveniently on a chart having only one absolute-amount scale. In general, the double scale treatment should not be used for presenting growth comparisons to the general reader." (Kenneth W Haemer, "Double Scales Are Dangerous", The American Statistician Vol. 2 (3) , 1948)
"[…] many readers are confused by the presence of two scales, and either use the wrong one or simply disregard both. Also, the general reader has the disconcerting habit of believing that because one curve is higher than another, it is also larger in magnitude. This leads to all sorts of misconceptions." (Kenneth W Haemer, "Double Scales Are Dangerous", The American Statistician Vol. 2 (3) , 1948)
"First, color has identity value. In other words, it serves
to distinguish one thing from another. In many cases it does this much better
and much quicker than black and white coding by different types of shading or
lines. […] Second, color has suggestion value. […] Red is usually taken to mean
a danger signal or an unfavorable condition. But since it is one of the most
visible of colors it is excellent for adding emphasis, regardless of
connotation. […] Green has no such unfavorable implication, and is usually
appropriate for suggesting a "green light" condition. […] Similarly,
every color carries its own connotations; and although they seldom make a vital
difference one way or the other, it seems logical to try to make them work for
you rather than against you." (Kenneth W Haemer, "Color in Chart Presentation", The
American Statistician Vol. 4 (2) , 1950)
"Seeing color isn't always as simple as it may seem. Some colors are not easy to see unless the conditions are just right; some are so easy to see that they overpower everything else; some are easy to see but difficult to distinguish. […] Large masses of color become too visible and easily overwhelm the entire chart. The more visible the color the easier it is to use too much of it." (Kenneth W Haemer, "Color in Chart Presentation", The American Statistician Vol. 4 (2) , 1950)
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