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Bivariate density plots are computed
exactly the same way as are contour plots (equal probability contouring).
This algorithm generates, in general, graphs which are most accurately
interpreted by our brains, in terms of relatively frequencies of subpopulations.
All contouring algorithms have advantages and disadvantages, but probability
contours have the fewest disadvantages. There
are two types of density plots: grey-scale and pseudo-color. They
are identical, except the color scheme is different. Grey-scale
may be more acceptable for publication; pseudo-color may be more
acceptable for slide presentations.
Density plot can be smoothed, or not. Note that
with smoothing off, every event gets a dot; thus, this plot is much
better than dot plots, since it allows the simultaneously information
of rare events (dots) and high-frequency areas (dots of a different
color).
You might choose low resolution to make data easier
to see in presentations: the small dots can be hard to see
on slides.
You may view a comparison
of all the bivariate displays for this
same data. |
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