Reading and understanding different graphs is an essential skill for anyone. If you use them in your PPTs and Excel sheets, you should know which graphs suit which type of data. In this article, we’ll see some of the different types of graphs and charts and how to read them.
Different Types of Graphs and Charts
The terms “graphs” and “charts” are sometimes used interchangeably, but they’re not entirely the same. Graphs represent a relationship between two or more variables. Charts represent a collection of data. Simply put, all graphs are charts, but not all charts are graphs.
Let’s look at 10 of the most commonly used graphs and charts, plus how to read them.
1. Line Graph
A line graph is one of the most commonly used graphs. It represents how two variables change with respect to each other. The simplest form of a line graph is one that illustrates how a particular variable changes over time.
The location of a point on a line graph is determined by its corresponding values on the x-axis and y-axis. For instance, in the above line graph, point B indicates that the average temperature on Monday is 8 °F. Similarly, by looking at the data on both axes, you can interpret what a particular instance in the graph means.
2. Bar Graph
A bar graph represents two or more variables using the height of rectangular bars. The taller a bar, the higher the value it represents. Bar graphs compare elements of a similar category with respect to a set of fixed values. To understand this better, let’s look at the below example.
Here, we’re comparing the ratings of six movies. On the x-axis, we have the movies reviewed, with the height of the rectangle boxes representing the rating each scored. On the y-axis, we have the scale for ratings—ranging from one to five stars.
This way, a bar graph allows for comparison between elements of similar categories. Note that there are multiple kinds of bar graphs. The one that we have used in the illustration above is called a vertical bar graph. Other kinds of bar graphs include:
Horizontal bar graphs Stacked bar graphs Grouped bar graphs
3. Pie Charts
A pie chart is a circular graph that is cut into multiple portions or slices. Each slice represents a unique proportion of the whole. Pie charts are very common given how easy it is to interpret them.
For example, in the image above, we see the division of a person’s income illustrated as portions of the entire pie. This gives us a clear idea of how much money that person spends on a certain thing.
4. Histograms
A histogram is similar to a bar graph in appearance and function, but the rectangle bars it contains are adjacent to each other. That is because the bars here display values that are proportionate to certain numerical intervals on the x-axis.
The above histogram represents the age distribution of people in a restaurant. The number of people aged between 20-29 is 10—represented by the height of the rectangular bar. Histograms are used to represent large data sets, and each variable range is called a “bucket” or “bin”.
5. Area Charts
Area charts or area graphs are similar to line graphs; the only addition is that the space between the x-axis and the line graph is filled with colors or textures. These are a blend of a line graph and bar graphs and are used to emphasize magnitude.
Area graphs are often used to compare the volumes of two or more quantities. The above graph shows the trends in revenue of two companies from 1980 to 2020.
6. Pictographs
A pictograph or pictogram is a visual representation of numerical data using icons. Observe the above pictogram to get a better sense of this. In it, the number of students who like a particular fruit is represented by the icons of the fruit itself.
For instance, five students in the class like apples, so the pictogram has five apple icons adjacent to it. Although pictograms are very easy to interpret, they are not ideal for representing large data sets or complex reports.
7. Scatter Plots
Scatter plots display how strongly two variables correlate with each other. The points or dots mentioned in the graph represent their values. If the correlation is strong, the dots will form a distinct pattern—appearing to be close to a line or curve. These are usually used when the data set is large and you’re trying to verify a seeming trend.
The above scatter plot shows how the prices of a product change over 20 weeks. Although it looks like a line graph, we can see how the points are not connected but are used to draw a line that represents a trend.
8. Spline Chart
A spline chart works on the notion that change follows a trajectory. Unlike a line graph that uses straight lines and takes sharp turns from one point to the other, a spline chart uses curved lines to show a rough approximation of the missing data points.
To make the comparison easy, we plotted a spline chart curve over the previous example of the line graph.
9. Funnel Chart
A funnel chart is used to represent stages of a linear process that form a funnel-like shape. It’s used to visually display how a quantity is reduced or lost at each stage. Each stage of the funnel represents a percentage of the whole.
You might have heard the term “sales funnel” before; it’s the most common portrayal of a funnel chart. The above example represents the sales of a product. We can see that only 3% of the people who have received an ad notification have actually purchased the product.
10. Venn Diagram
A Venn diagram is a graphic illustration containing two or more overlapping circles that show the logical relationship between two or more sets of items. Basically, it helps visualize the differences and similarities between two or more things.
Learn How to Read a Graph
Graphs may look easy to understand, but accurately interpreting what they represent can be difficult, more so if you’re dealing with a complex one.
If you’re someone who uses graphs professionally, it’s essential to choose the right graphs to make interpretation easy for the readers.
