Graphs and charts are nothing new to us unless you are just a kid in your early stage of the school (I assume you’re not). Graphing is an important technique for anyone and everyone who’s involved in data to come to conclusions and also make decisions that could be much harder without the use of visualization. OK, given below is an example of a dataset for sales for last 4 financial years.
Sure with a quick glance, you can get some idea of the sales but it’s pretty obvious that you can learn nothing important. But put that into a graph,
now you end up seeing some important trends in your sales. So you decided to put your data into a graph, but choosing the correct type of graph to display your data could seem difficult because there are many types of graph to choose from. There could be a sales bar chart, pie chart, line chart blah… bla…bla…So the purpose of this article is to know when to use the two most common types of graphs, which are bar and line charts.
Before we go further into the matter, let us look into the graphing rules. Bar charts are used to display data with unique categories trying to show the difference between the groups, just like the one below.
Whereas the line graph shows changes in one variable or changes over time. In a line graph, one variable has been divided up and is displayed on the x-axis as shown in the below graph as time is the variable that is changing
Ok, let’s take a real-life scenario to make it more practical, let’s say that you’re running a supermarket business globally and you need to see your sales performance for the previous years. Bar charts are ideal for such scenarios where it helps visualize comparison across different categories with height when trying to measure.
Each category is independent and no specific connection to each other except for the fact that they are all fall under same category (Ex. Relationship between London & Tokyo will be same as Mumbai & Tokyo except for the fact that all are locations)
Now let’s say that you need to see how your sales performed over the past few years by months, bar charts would not be an ideal choice as there are too many variables. So here, line charts would be ideal, just look at the below example.
We use a line graph to Identify specific pattern (Movement of Line) of a measure (Ex. Total Sum of Sales) over an incremental change of an independent variable ( Transaction date)
Be it a Bar or a Line or even a Pie chart or any other graph, they really help us visualize and understand a different perspective of a dataset. All you need to do is to decide which one to use in order to extract the right information you need. In this case, if it’s a categorical data, Bars are ideal to present them & if you have continuous data then go for a line.