The purpose of a graph is to show a representation of numerical facts in visual form so that they can be understood quickly, easily, and clearly. Thus, graphs are visual representations of the collected data; they are also more effective for comparing. Data can also be presented in the form of a table; however, a graphical representation is easier to understand and can be presented more creatively.
So in this article, we will understand graphs, types of representing data, and the applications in real life.
Following are the different types of graphical representations:
1. Line Graphs: A line graph compares two variables through visual representation, shown on the x and yaxis. It shows the information through a continuous line drawn between all the points on a grid.
2. Bar Graphs: To show a comparison between different categories, we can use a Bar Graph. It consists of two or more parallel vertical (or horizontal) bars (rectangles).e.g. between two grades, two companies, etc.
3. Pictographs: A pictograph conveys statistical information through pictures and symbols. One should carefully use a pictograph because the graphs may, either accidentally or deliberately, misrepresent the data. That is why this type of graph should be visually accurate.
It helps in expressing a large amount of data in a more straightforward form. Further, the symbols in a pictograph help attract attention and are a smart way of representing data. In fact, they are relatively easy to read since we can get all the information in one glimpse and do not need a great deal of explanation.
4. Pie Charts: Pie charts are circular charts divided into sectors according to the value they represent. The arc length of each sector is proportional to the quantity it represents.
We generally use pie charts to show percentage or proportional data. Usually, the percentage represented by each category is provided next to the corresponding sector of the circle. In a pie chart, the angle of each sector represents the fraction, out of 360 degrees, of that data value. We should always label them, either directly on the pie chart or by using a colorcoded key.
5. Frequency Diagrams And Polygon: A frequency diagram, which is also called a line chart or a frequency polygon, shows the frequencies of different groups. A frequency polygon is a graphical device that helps in understanding the shapes of distributions. Although they serve the same purpose as histograms, they are also helpful for comparing sets of data. This is also a good choice for displaying cumulative frequency distributions. It is used to measure/analyze how frequently a particular observation occurs. It might be marks of a student per year for a few years, runs, etc.
6. Scatter Diagrams: A scatter diagram is a tool for comparing relationships between two variables for determining how closely the two variables are related. It is also called a Scatter Graph or Correlation Chart. In Scatter Graph, One variable is plotted on the horizontal axis, and the other is plotted on the vertical axis. Where there is less scatter that is about the bestfit line, the stronger the relationship is between the two quantities. If the points are close to the bestfit line, we say that there is a strong correlation.
If the points are loosely scattered, there is a weak correlation. There is zero correlation if there is no linear relationship between the variables in other words, if we can't draw a meaningful best fit line. If the best fit line slopes upward like it does below, then the things we are comparing go up together. We say that there is a positive correlation. If the line slopes down, the 'dependent variable' decreases as the 'independent variable' increases.
A bar graph is used to show a comparison among categories. It may consist of two or more parallel vertical (or horizontal) bars (rectangles). A bar chart is used to compare two or more values with a small set of results.
Properties of Bar Graphs
Construction of a Bar Graph
Types of Bar Graphs
There are two types of Bar Graphs:
Depending upon the choice of the axis as the base either Vertical Bar Graph or Horizontal Bar Graphs are used. Let us take an example of a bar graph showing the comparison of marks of a student in all subjects out of 100 marks.
With the bar graph, we can also compare the marks of students in each subject other than the marks of one student in every subject. Also, we can draw the bar graph for every student in all subjects.
Data that changes continuously over periods of time is displayed by a line graph. A line graph is often used to show a trend over a number of days or hours. It shows the changes in the data over a period of time. We plot a line graph as a series of points, which are then joined with straight lines. It is not necessary that the ends of the line graph have to join the axis.
Properties of a line graph
For example, the line graph showing the number of buses passing through a particular street over a period of time can be represented as follows:
The following are the types of line graph. They are:
One important use of line graphs is to track the changes over a short and long period of time. It is also used to compare the changes over the same period of time for different groups. If small changes exist in the data, it is always better to use the line graph than the bar graph. For example, a company finance team wants to plot the changes in the cash amount that the company has on hand over time. In this case, they use a line graph and plot the points over the horizontal and vertical axes. It usually represents the time period of the data.
In real life, you might have observed that if you use more of a facility, you have to pay more for it. If more electricity is consumed, the bill is bound to be high. If you use less electricity, then the bill will be lesser. This instance is an example of a situation where one quantity affects another. The amount of electricity bill depends on the quantity of electricity used. We can say that here, the quantity of electricity is an independent variable (or sometimes controllable variable) and the amount of electricity bill is the dependent variable. A graph represents the relation between such variables.
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