Databases Reference
In-Depth Information
Figure
9-11
provides a trend of one variable compared to a moving average (upper
bound and lower bound), in this case the salary paid to employees are tracked against an
industry average over a continuous time frame.
Figure 9-11.
Line graph depicting comparison of salaries paid to the employees against
the industry standard over the years
■
You should be using line graphs when the change in a variable or variables clearly
needs to be displayed and/or when trending or rate-of-change information is something
you would like to highlight to the users.
Note
Bar Graphs
Bar graphs are most commonly used visualization technique. These are used for
comparing the values of different categories. Values of a category are represented using
the bars with the length or height of each bar representing the quantity.
Bar graphs are very effective when the values are distinct enough and the differences
in the bars can be easily detected. When the values (bars) are very close together or there
are large numbers of values (bars) that need to be displayed, bar graphs become clumsy
and it becomes difficult to compare the bars to each other.
Figure
9-12
provides a trend of anomalies in salary given by an IT company over the
years, interesting to note the positive and negative variances compared to an industry
average.
