"All of this information might be useful and even, for certain purposes, necessary. It is, so to speak, the statistical data of the question. But it yields no picture. A map or a globe gives us this mental picture almost in a flash. And that is precisely the use and service of a chart." (Carl Snyder, [in Karl G Karsten, "Charts and Graphs", 1925] 1923)
"A circular, like a square, area varies with the square of its linear measurements. If you make the radius of one circle twice as great as the radius of the other, the first area will be four times as great as the first. If you make the areas proportionate, the radii must be in the relation of 1 to the square root of 2. Both circle and square require the more or less tedious computation of square roots and repay this labor with inaccurate and ambiguous results." (Karl G Karsten, "Charts and Graphs", 1925)
"A curve cannot, however, always be used in the place of a bar-chart, for the line which connects the various points implies that the data itself can be considered connected. Much data can not be so considered. A careful inspection of the data will soon show whether it is connected or not, for the stubs of connected data always form a variable." (Karl G Karsten, "Charts and Graphs", 1925)
"A further detail of the 100% bar and its labelling, is the scale. This should generally be in hundredths or percents. The data may be entirely in absolute quantities, but nevertheless the scale should show percentages. To prevent the confusion of scale and divisions of the bar, the scale should be outside the bar, and the best practice seems to be to indicate the scale by little notches or short perpendicular lines dropped below the bar, from its lower edge." (Karl G Karsten, "Charts and Graphs", 1925)
"A quantity can always be illustrated by a straight line, or, as it is commonly called, a 'bar'. Bars are the simplest and often the best form of erate The total length of the line then represents the total value of the quantity. When we speak of a line in charting, we do not mean an imaginary straight line having neither width nor depth, for that would be invisible and could not, of course, be actually used in illustrations. In its place we use the bar, with a visible width (and the actual depth or thickness of a layer of ink). But it is still proper to speak of this bar as being a line or one-dimension chart, for its width and thickness are constants, necessary to give visibility to the line, and its length alone is significant." (Karl G Karsten, "Charts and Graphs", 1925)
"A series ot quantities or values can be most simply and often best shown by a series of corresponding lines or bars. All bars being drawn against one and the same scale, their lengths vary with the amounts which they represent." (Karl G Karsten, "Charts and Graphs", 1925)
"Another principle which will quickly appeal to your common sense, is the rule that when zero is real, the zero-line should be extra heavy to make it prominent. Remember that it takes the place of the floor or lower end of the bars in the bar-chart. It should stand out, therefore, in such a way that the reader can easily grasp its significance and compare with it the heights of the points on the curve. The rule is particularly important in cases where the chart extends down below the zero line into the negative side in order to show negative and positive values. On the same principle the 100% line, when it occurs in a chart, should be similarly heavy as it also may be considered a base for zero points, being the point of zero loss or gain. In fact, the rule may be extended to all cases of lines showing significant constant values, and the zero line should not be heavy, unless it has a special significance." (Karl G Karsten, "Charts and Graphs", 1925)
"Bar-charts are most flexible and can be varied to suit the individual whims of the maker. In general, however, there is one style or form which will be found most satisfactory. It consists of a horizontal grouping of bars alongside of the data. The chart is arranged in tabular form, with items or stubs in a column to the left, with figures in a column beside the stubs and with bars in a column beside the figures. Several columns of figures are sometimes desirable, just as in the table of data, to show sources or original figures from which the charted figures are obtained. In any case, the bars should represent the most important set or column of figures, and there should be normally but one column of bars."(Karl G Karsten, "Charts and Graphs", 1925)
"Having confessed so little patience with the doctrine of the incomprehensible per se, we have naturally sought to empty the entire bag of tricks, and to tell the whole story of the chart in the simplest words that we command. Our belief has been that it is a lesser sin to be too easily understood than never understood at all. But at the same time, we have sought to make the story full and complete." (Karl G Karsten, "Charts and Graphs", 1925)
"Having prepared your data, you will next decide upon a 'scale’ or ratio of reduction to use in the drawing, that is, what value or distance on the actual floor shall be represented by each space or distance between lines on the paper. It is important to pick a scale which is neither too large nor too small, so that the drawing will be the right size on the sheet." (Karl G Karsten, "Charts and Graphs", 1925)
"In all chart-making, the material to be shown must be accurately compiled before it can be charted. For an understanding of the classification chart, we must delve somewhat into the mysteries of the various methods of classification and indexing. The art of classifying calls into play the power of visualizing a 'whole' together with all its 'parts'. Even in the most exact science, it is not always easy to break up a whole into a complete set of the distinct, mutually exclusive parts which together exactly compose it." (Karl G Karsten, "Charts and Graphs", 1925)
"In fact, it can be laid down as a general rule that both the compound and the multiple bar-charts are too elaborate and complicated. A chart is always better the simpler it is, and we should make strong efforts to simplify these charts, and if possible reduce them to simple bar-charts. It usually pays well for sacrifices we make in this way, in legibility and interest to the reader, and after all, the chart of this type 1s generally directed at a reader, rather than at the maker." (Karl G Karsten, "Charts and Graphs", 1925)
"In short, the pie-chart appears to be a two-dimension (area) chart used for one-dimension data. The fact is, however, that, as in the case of the 100% bar, the area of the chart varies directly with one dimension, the other dimension being constant. In the 100% bar the width of the bar was constant in the 100% circle the radius must be constant for all circles compared. Then the area of the segments varies directly with their arcs or angles and the chart has but one significant dimension. It is only an apparent exception to the rule." (Karl G Karsten, "Charts and Graphs", 1925)
"In short, the rule that no more dimensions or axes should be used in the chart than the data calls for, is fundamental. Violate this rule and you bring down upon your head a host of penalties. In the first place, you complicate your computing processes, or else achieve a grossly deceptive chart. If your chart becomes deceptive, it has defeated its purpose, which was to represent accurately. Unless, of course, you intended to deceive, in which case we are through with you and leave you to Mark Twain’s mercies. If you make your chart accurate, at the cost of considerable square or cube root calculating, you still have no hope, for the chart is not clear; your reader is more than likely to misunderstand it. Confusion, inaccuracy and deception always lie in wait for you down the path departing from the principle we have discussed - and one of them is sure to catch you." (Karl G Karsten, "Charts and Graphs", 1925)
"In short, the scales on which a curve is drawn can affect very much our impressions of the data by magnifying or minimizing the apparent movements of the curve itself. Of course, this does not mean that the relative height from the base-line of the various points on the curve have been altered. If you have been careful to show the base-line always, the base-line itself will approach nearer to the curve as the vertical scale is reduced and the wiggles are flattened out, and will recede farther from the curve as the vertical scale is enlarged and the wiggles are exaggerated. But it means that the oscillation or fluctuation of the curve will have been made to appear more violent or milder according as either of the scales is changed. And it therefore behooves us to give serious thought to the matter of scales before’ we determine upon them finally for any particular chart. As a matter of fact, we may have to try out several combinations of scales before we find one which gives just the right amount of emphasis to curve fluctuations to suit us." (Karl G Karsten, "Charts and Graphs", 1925)
"In the labelling of the pie-chart, you will furthermore encounter typographical difficulties. It is not ordinarily a good thing to make a reader crane his neck at various angles to read writing along every point of the compass, so you should not, as so many do, write on radii from the center of the circle. On the other hand, unless the chart and its segments are very large as compared with the size of the printing, you will introduce tricky optical illusions if you write all labels in the same directions inside the segments." (Karl G Karsten, "Charts and Graphs", 1925)
"Moreover in the pipe-organ cr vertical-bar chart, we first encounter labelling or data difficulties. And if there is one motto which we should like to print at the bottom of every page in bold-face type, as do the publishers of other valuable reference-books, it is this: 'Never separate your chart from its data'. On the contrary, incorporate the data in the chart. For a chart without its data is a poor lost thing indeed. And the unhappy reader wishing to know what it means must hunt and hunt and hunt till he locates the particular information in some distant table. As a matter of fact, he won’t do it, for before he has found his data he has lost his interest in the matter, and then what good is your chart." (Karl G Karsten, "Charts and Graphs", 1925)
"Most of the good things in this world involve some sacrifice. Curves are no exception. In a curve the direct visible connection between the curve itself and the zero line, or x-axis, is sacrificed. As time goes on and you become more and more used to the curve chart, you will begin to think of its values as in some mysterious manner floating disembodied along the connecting line which forms the curve. You will be tempted to forget that the quantities rest very substantially upon the floor (base line, zero line, x-axis or whatever you want to call it), and that it is only their tops which reach the points plotted in the curve. And forgetting this, you will try to save space by omitting the zero line and lower part of the chart, and by showing only that small portion or band of the chart through which the plotted curve travels." (Karl G Karsten, "Charts and Graphs", 1925)
"Multiple curves are far better than multiple bar charts. A number of curves wiggling across the page at the tops of invisible bars are eminently more satisfactory than actual bars interlarded. In the first place, comparison of several series of data is greatly facilitated in curves - because each set has been condensed and simplified into a single line. There is no difficulty in comparing values of each series with each other. In the second place, such a comparison is more accurate in curves because all similar points on various sets or series have been brought together upon a single vertical line." (Karl G Karsten, "Charts and Graphs", 1925)
"Note also, and this is important, that if through standing too close you should take a picture showing only the upper ends of the upright boards, but not their full lengths, you would consider the resulting picture not only a failure but actually deceptive. In other words, you must not omit the zero-line or base-line. While you would succeed in showing the variation of the top ends more clearly you would no longer have comparable lengths." (Karl G Karsten, "Charts and Graphs", 1925)
"Now figures are not in themselves necessarily dry and dull - in fact the figures of your bank-account may be very engrossing to you. But figures on uninteresting subjects are a sure cure for insomnia, to all of us. And it goes without saying that if the figures are not of consequence, the chart of these figures will deserve equally little attention. The point is that a chart is as weak as its own data, and a chart-maker must carefully weigh and consider his data before permitting himself the pleasure of illustrating them with a chart." (Karl G Karsten, "Charts and Graphs", 1925)
"The advantage of the pie-chart is psychological. It instantly commands the reader’s attention. A circle is, of all geometrical patterns, the easiest resting spot for the eye. The fact is well known to advertisers, who frequently use circles and circular outlines to draw attentica to their advertisements. Hence if your chart is designed for publication, or for presenta tion to readers whose attention may be easily diverted, you will find the pie-chart a powerful means for presenting your facts. Attention will be focused upon it at once, and it is as simple to understand as its name - far too simple for anyone to misunderstand. Because it is circular, there is no question but that it represents a whole and the various slices of the pie belong to their respective items." (Karl G Karsten, "Charts and Graphs", 1925)
"The chief value of the 'pipe-organ char' [aka bar chart] as it is sometimes called, lies in the realistic picture it gives of quantities. From a base line these quantities are seen to rise the full length of the bars, as so much substantial material stacked neatly in piles where we can compare them. We view them from the ‘level or floor on which they are piled. We do not have to climb up and get a bird’s-eye view of them as in the ordinary bar-chart, where we seem to be looking down upon rows and rows of goods, but we see them from a natural view-point. Nor do we rely upon an arbitrary arrangement by which their left ends have been brought together as in the bar-chart, but we know instantly that if they are piled up, it is their tops which we must watch. The pipe-organ chart finds instant response in our minds, and appeals to us as both logical and natural. A child can comprehend it." (Karl G Karsten, "Charts and Graphs", 1925)
"The disadvantages of the pie-chart are many. It is worthless for study and research purposes. In the first place, the human eye cannot easily compare as to length the various arcs about the circle, lying as they do in different directions. In the second place, the human eye is not naturally skilled at comparing angles - those angles at the center of the circle, formed by the various rays or radii and subtending the various arcs. In the third place, the human eye is not an expert judge of comparative sizes of areas, especially those as irregular as the segments of parts of the circle. There is no way by which the parts of this round unit can be compared so accurately and quickly as the parts of a straight line or bar. Moreover, when, as frequently happens, several pie-charts are shown together, the various slices in one chart cannot be so easily compared with the corresponding slices in the next, as can the various parts of one 100% bar with corresponding parts of another bar." (Karl G Karsten, "Charts and Graphs", 1925)
"The division of a 'whole' into its 'parts' is logically one of the first steps in any analysis. Usually the graph illustrating this division belongs at the beginning of a statistical report. Thus, if your report covers the sales of the company, your first chart would break up total sales into the individual sales for each line or for each district. The remainder of the report, treating of details of the various 'parts' (e.g., lines or districts) will then follow a summary chart which has established their relative importance." (Karl G Karsten, "Charts and Graphs", 1925)
"The greatest contribution to chart-making, from any single source, is the Gantt Progress Chart. This chart is, unquestionably, the most powerful graphic device for business and for all executive and managerial purposes. While the description has been rather full, as given herein, it is by no means complete; and the Gantt charting methods, in all their co-ordinated ramifications, constitute an independent system of accounting and of executive control,in this [...]" (Karl G Karsten, "Charts and Graphs", [preface] 1925)
"The technique of bar-charts is so simple and they are so very effective, that they should be used freely in printed text-matter. No drawing or plates are needed. Printers have 'rules' as they call them, which can be used to make solid bars, and these rules can easily be set up together with the type. The scale and field can be omitted and the bars alone will effectively tell the story of the main figures in the table. The combined table and chart can be used in printed text just as well as the table alone." (Karl G Karsten, "Charts and Graphs", 1925)
"These apparently arbitrary rules of thumb are justified only so long as they serve to produce the best results. Your real purpose is to show the data most clearly and simply, either to yourself or to someone else. The chart is a window, as it were, through which the reader looks out upon an illuminating picture of the facts he is considering. Through this window he sees, if you like, a chain of mountains, whose height tells him the values or quantities he is considering. That he may see them to the best advantage, the window must be low enough for him to see the base of the mountain-range and high enough for him to see at least some sky above the highest peak. In general, the best view of the mountains would show neither too much nor too little clear sky above. And if the window is crossed with a framework for small window-panes, he can further judge of heights by the crisscross window-pane lines. Your curve is the silhouette of that mountain-range, your field the tiny window-pane outlines, and you, the chart-maker, must use your own judgment and artistic sense to place the reader’s chair near or far, high or low, in front of that window, to give him the clearest view." s it were, through which the reader looks out upon an illu- minating picture of the facts he is considering. Through this window he sees, if you like, a chain of mountains, whose height tells him the values or quantities he is considering. That he may see them to the best advantage, the window must be low enough for him to see the base of the mountain-range" (Karl G Karsten, "Charts and Graphs", 1925)
"This practice of omitting the zero line is all too common, but it is not for that reason excusable. The amputated chart is a deceptive one, tempting the average reader to compare the heights of points on the curve from the false bottom of the amputated chart-field, rather than from the true zero line, far below and invisible. A curve-chart without a zero line is in general no whit less of a printed lie, than a vertical bar-chart in which the lower part of the bars themselves are cut away. The representation of comparative sizes has been distorted and the fluctuations (changes in value) exaggerated." (Karl G Karsten, "Charts and Graphs", 1925)
"Throughout your study of charts you will find some which are more useful for popular consumption than others, but you will not find many which are more purely popular in appeal than the 100% circle or pie diagram. For analytical purposes it has nothing to recommend it, but for sensational values it is in general without an equal." (Karl G Karsten, "Charts and Graphs", 1925)
"To make a bar-chart popular, knock it over flat on its side, so that the bars stand up on end. Simple, isn’t it? But that’s the rule. There being nothing more to discuss in the matter of making popular bar-charts, we are tempted to close the dis- cussion at this point and produce a pleasant surprise to all. But the vertical bar-chart [aka column chart] is rich in suggestions for the higher forms of charts which we are approaching, and it deserves a close study." (Karl G Karsten, "Charts and Graphs", 1925)
"We have so consistently inveighed against the use of areas to illustrate quantities that the reader will indeed be surprised at some coming retractions. [...] But the fact is that we now propose to turn to advantage the very feature of areas which has previously been their greatest fault. [...] We now come to data in which we wish to show simultaneously three ratios or sets of ratios, one of which is always the product of the other two. In other words, we wish to show two factors or sets of factors and their product." (Karl G Karsten, "Charts and Graphs", 1925)
"When several curves are shown upon the same chart, it is often desirable to use different scales for them. That is, the same horizontal lines may be given two or even more different values for different curves. But even in these cases, it is better to place both scales, once and for all, at the left hand side. The practise of placing one of these scales at the right hand side, and another at the left hand side, has little to recommend it. Theoretically, at least, the left hand end of your chart is normally the y-axis itself, and the scale or ‘scales should logically be attached immediately thereto. In practice this logical position is justified." (Karl G Karsten, "Charts and Graphs", 1925)
