BUBBLE CHART
A Bubble
chart is a type of chart that displays three dimensions of data. Bubble charts can facilitate the understanding of social,
economical, medical, and other scientific relationships. A bubble chart
is a variation of a scatter chart in which the data points are
replaced with bubbles, and an additional dimension of the data is represented
in the size of the bubbles. Just like a scatter chart, a bubble chart does not
use a category axis — both horizontal and vertical axes are value axes. In
addition to the x values and y values that are plotted in a scatter chart, a
bubble chart plots x values, y values, and z (size) values.
We can use a bubble chart instead of a
scatter chart if we have data that has three data series and each series contains
a set of values. The sizes of the bubbles are determined by the values in the
third data series. A bubble chart is very useful when it comes to presenting
data that has a requirement for the inclusion of magnitude or extent in the
presentation, such as in scientific, mathematical and social data yields.
The issue in a bubble chart however, is
that it is quite intricate to plot a data-proportionate item for the third
variable. Given that an accurate presentation of the third variable,
as in the size of the bubble, must have an area that is equal to the
square-root of the value of the said third variable.
RADAR CHART
A Radar chart is a graphical method of
displaying multivariate data in the form of a two-dimensional chart of three or
more quantitative variables represented on axes starting from the same point.
The relative position and angle of the axes is typically uninformative. A radar chart graphically shows the size of the gaps among
five to ten organizational performances areas.
The chart displays the important categories of performance and makes
visible concentrations of strengths and weaknesses.
The radar chart is also known as web chart,
spider chart, star chart, star plot, cobweb chart, irregular polygon or polar
chart.
The radar chart is a chart and/or plot
that consist of a sequence of equi-angular spokes, called radii, with each
spoke representing one of the variables. The data length of a spoke is
proportional to the magnitude of the variable for the data point relative to
the maximum magnitude of the variable across all data points. A line is drawn
connecting the data values for each spoke. This gives the plot a star-like
appearance and the origin of one of the popular names for this plot.
Radar charts are a useful way to display
multivariate observations with an arbitrary number of variables. Each star
represents a single observation. Typically, radar charts are generated in a
multi-plot format with many stars on each page and each star representing one
observation. The star plot was first used by Georg von Mayr in 1877.Radar
charts differ from glyph plots in that all variables are used to construct the
plotted star figure. There is no separation into foreground and background
variables. Instead, the star-shaped figures are usually arranged in a
rectangular array on the page. It is somewhat easier to see patterns in the
data if the observations are arranged in some non-arbitrary order (if the
variables are assigned to the rays of the star in some meaningful order).
One application of radar charts is the
control of quality improvement to display the performance metrics of any
ongoing program.
They are also being used in sports to
chart players' strengths and weaknesses, where they are usually called spider
charts.
A radar chart shows how a team has
evaluated a number of organizational performance areas. It is therefore essential that the initial
evaluation include varied perspectives to provide an overall realistic and
useful picture of performance.
Further, radar charts are visually
striking, and can add interest to what would otherwise be a dry data
presentation.
By:
Annie Basumatary
14070
Group G
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