Re: [graphics-dev] Alpha version of the chart reimplementation available for downloa

[Leonard Mada]

Hello What in particular disturbed you about the 3d charts in the new chart (That's what I suppose you mean by new 3D pie-charts)? I was disturbed that so much effort is put into expanding these 3D charts, when virtually any high-ranking statistician warns against their use. To quote Prof. Feinstein: (applies to both 3D bars and 3D pies) > A particularly lamentable custom is “volumizing”— a tactic that converts the two-dimensional bar > to a three-dimensional post. Since the second-dimension was needed only for labeling, the third-dimension > is completely unnecessary. Its use is an act of “marketing,” not scientific communication. > (Examples of these abuses for contrasts of groups will be shown later in Chapter 16.) And a somewhat similar concept: (the worse pie-chart example) > The basic idea of a pie graph is abandoned because each category is given about the same angular slice, > and the circular shape has been converted to a quasi-ellipse for portraying a third dimension. Indeed, as I already stated, 3D charts DO NOT add any statistical benefits and should be strongly discouraged!!! Of course it does not add information, it's just that people like 3d charts for presentation. Imagine what would happen if we suddenly dropped the support for all 3d chart types. We can simply not do this. And besides, we don't want to. I believe it is the duty of a good program to *warn* the user when he takes the wrong decision. Let the 3D charts sit there, BUT when a user selects one for use, warn him about this and offer an explanation, why a third dimension is not desirable. I would also suggest to ask a number of high-ranking statisticians to wright this explanation, so that - at least some of the users - would abandon the 3D chart use. e.g. Tell me please, which is bigger, 'Column B' or 'Column C': You will wonder, that both segments are equal (38%). I created this pie chart with the *default* settings in Calc, so it is really NOT me choosing a particular very wrong setting. IT WILL ALWAYS HAPPEN when having two similar values that together add to more than 50% (=> one segment will be drawn in the back and will look rather small, and the next one comes in the front, looking rather big). Another great problem arises when one has to compare segments from *2* *different* *pies*:  - IF the segments are not located in the same position (e.g. 3 o'clock on one pie, BUT 6 o'clock in the 2nd one), you would again come into big trouble. Of course, you should always use 3d charts with care. If you have a 3d pie which you view almost from above, there is no big difference to a 2d pie, except that <<some people find this more appealing.>> <<Some people>> means most (if not all) significant statisticians, that is the difference. PROBLEMS ========= There are a number of problems even with the standard pie-chart (2D). I mentioned one in my first post.  - very small values are NOT easily displayed and NOT easy to see Therefore I would recommend putting some effort into solving this problem. I would also like to be able to rotate (clockwise or counter-clockwise in 2D, NOT 3D) the pie chart (this is especially useful, when one wants to align 2 pie charts). Also, I would sometimes want to swap 2 segments. Another problem are charts with negative values. I wanted recently to create a pie chart, highlighting the difference between 2 groups (2 pie charts), so I created the difference between the proportions. SOme were positive, some were negative. I would have welcomed a mechanism to automatically group the positive proportions vs the negative proportions (they must sum up to 0, so both groups would have occupied half of the piechart). Instead, the values were used as absolute values AND therefore were intermixed, bringing NO meaning. There are many other issues that could be improved. Kind regards, Leonard Mada