Bar Chart and Bar Graph - Exam Syllabus - Study Material and Important Question

What is Data Introduction ?

Data Introduction is the act of transforming data with the objective of extracting useful information and facilitating conclusions on the basis of the given data. Depending upon the type of data and the questions, we might be required to apply certain statistical tools with various methods to represents the given data.

What is Data ?

Data is means to represents facts, concepts or instruction in a formalized manner suitable for communication, interpretation or processing by humans or other automatic models.

In other words, propositions like measurements or observations of a variable, which may comprise numbers, words or images can be quantified with the help of data.

Data can be a numerical or non-numerical fact and figure related to a particular social, economic or political event etc.

Let us see some examples of data :
Yesterday the Sensex closed at 14,004 points.
25% of the total population of India is below The poverty line.
In the last general elections in India, 40% of the total seats were won by regional parties. Data can be further understood to be an agent to cause the sentiments and even sometimes it can be effect also.

It the data given is distinct and separate, i.e. It can be counted (1, 2, 3……), then it is known as Discrete Data. For example, population of a country, production of cars in a manufacturing plant.

However, if the data takes any value within a finite or infinite interval, then it is known as a Continuous Variable. For example, the percentage of sugar in mangoes or weight/height etc…, are continuous variables.

 

Bar Chart / Bar Graph

The bar chart, in comparison to the pie chart is more versatile in representing data. It has been proven that representation using lengths as in the case of bar charts is a better indicator of data vis-à-vis pie charts wherein data is categorized in terms of areas.

In the above diagram, the same data has been represented length-wise in the bar chart and area-wise in the pie chart. Obviously, it is easier to see the contribution of the various segments in the bar chart than in the pie chart.

A therefore, is a chart with rectangular bars of lengths proportional to the values which they represent. Usually, the terms ‘bar chart’ and ‘bar graph’ are used interchangeably. It should also be noted that in a bar chart, what matters is the length of the bar and not the width of the bar.

Example: The following bar chart represents the number of seats won by different parties in the last general election.

 

Significance of Bar Charts

Following are the major specialties of bar charts :
Unlike the pie chart, a single bar chart can be used to compare two, or more than two continuous variables.

Example: The following bar chart represents the number of seats won by different parties in two general elections:

Since the length parameter is easier to study than the area parameter, a bar chart gives a quick understanding of the various ranks. Hence the time taken to understand the data becomes considerably lower in a bar chart as compared to other formats of data presentation.

 

Types of Bar Charts

There are three types of bar charts :

1) Normal Bar Chart

This is a simple bar chart with the values of different segments represented in the form of bars, which could be either horizontal, vertical or both.

Example: The following bar chart represents the crime cases reported in Delhi in 2007:

Bar Chart with Vertical Bars

Bar Chart with Horizontal Bars

Bar Charts with 3-D Effects

2) Stacked Bar Chart Value-wise

When the same variable is to be represented on more than one parameters like; year etc…,then we can have a stacked bar chart.

Stacked Bar Chart Percentage-Wise

The only difference between value-wise and percentage-wise bar charts is that in the former we apply values to stack that bars and in the latter we apply percentages.

Stacked Bar Charts are also known as Cumulative Bar Charts.

Example: Here, we will see the same data in normal bar chart, value-wise stacked bar chart and stacked bar chart and stacked bar chart percentage wise

3) Normal Bar Chart

Following things can be observed in the above bar chart :

Bars representing different crimes in different years are proportional to the crimes reported.
The above bar chart takes the minimum values as 100, however the same bar chart could take the minimum values as 0 or 50 or anything else as well. The question here is, what will happen if we take the minimum value as 150?

Since some of the values are less than 150, what will happen to those? Find out yourself without using a computer.

Following things can be observed in the above stacked bar chart:

The total number of murders have been added up in one bar and the different years are shown as a part of that total.
The same data could also have been represented by taking the sum of all the crimes reported in a particular year as a total, and the individual crimes as a part of that total.

Stacked Bar Chart Percentage-wise

Following things can be observed in the above stacked bar chart :

  • The total number of murders have been added up and they equal to 100%; and the mureders reported in different years have been taken as a percentage of that total.
  • The same data could have been represented by taking the sum of all the crimes reported in a particular year as a total, and the individual crimes as a part of that total.

 

Important Solved Examples for Bar Charts

Directions for questions 1 to 5: Refer to the following bar graph and solve the questions based on it.
The following bar chart shows the monthly expenditure of a family comprising of five persons over a period of seven months during three different years.

Question 1) In any of the given years, which month see the maximum percentage increase in expenses with respect to the previous month?

Answer: April. This question can be solved by visual inspection.

Question 2) What is the average monthly expenditure of the whole family in the year 2000?

Answer: Rs. cannot be determined. To find the average monthly expenditure during the year 2000, the total income for the year has to be known. In the chart, the income of only seven months is known. Therefore it cannot be determined.

Question 3) In April 2000, What was the percentage increase in expenditure over April 1999?

Answer: 1.2%.
value (April 2000) = 316
Value (April 1999) = 312
Approximate % age increase = 1.2%

Question 4) Which period has shown the same change in trend across all the given three years?

Answer: March-April. The same increasing trend is seen every year during the period March-April.

Question 5) For how many months of the given years the expenditure has been consistently increasing or decreasing?
Answer: 1. Only April Satisfies these conditions.

 

Important Questions for Bar Chart - From Previous Year Papers

This part will cover Bar Graph Syllabus of IBPS Bank Clerk Exam.

 

 

Online Video for Bar Chart - Must watch - very helpful

 

 

 

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