-

A line graph, also called a line chart, is a graphical display of information that changes continuously over time. It has two axes. The x-axis (abscissa) of a line graph shows the occurrences and the categories being compared over time and the y-axis (ordinate) represents the scale, which is a set of numbers that represents the data and is organized into equal intervals.

It is important to know that all line graphs must have a title. A line graph also includes a key that represents the event, situation, and information being measured over time. The lines in the graph can either descend or ascend based on the data. We now list out some of the advantages and disadvantages of line graphs.

1. These are suitable for representing the data points, i.e. given one variable, the other can easily be determined.
2. Convenient to plot time graphs along the x/y axis as it clearly depicts the rise and fall of data points. By correct selection of scales for each axis (time on the x-axis and the change is measured on the y-axis) the reader can easily observe the changes in one group over time. These help to detect the trends pretty early enabling the viewer to make predictions about the data that is yet to be recorded.
3. These enable observation of both short-term and long-term changes. This aids easy comparison of two or more values.
4. Simpler to construct and read than bar graphs or histograms.
5. Projects patterns and trends over time better than other graphs.
6. Requires minimal written or verbal explanation.
7. The time-series data relating to two or more related variables i.e., phenomena measured in the same unit and belonging to the same time period can be displayed together in the same graph using the same scales for all the variables along the vertical axis and the same scale for time along X-axis for each variable. The technique of drawing two or more line graphs on the same graph facilitates comparisons between the related phenomena.

1. It does not tell us anything about the causes behind the fluctuation in the data.
2. It does not reveal much about the skewness or kurtosis of the data.
3. The technique of drawing two or more line graphs on the same graph facilitates comparisons between the related phenomena. However, its use should not be recommended if the number of variables is large, say, more than 4. In such a case the different line graphs which may intersect each other become quite confusing and it becomes quite difficult to understand and interpret them.
4. It can be used to manipulate or deceive the general public. A scammer can deliberately change the scales on the X and Y-axis in order to lead to misleading conclusions.

#### References:

1. Business Statistics – SC Gupta and Indra Gupta.
2. Basics in Nursing Research and Biostatistics – Sreevani Rentala.