BAR CHART (OR GRAPHS) AND THEIR USES IN ECONOMICS, What is a bar chart? Bar chart or graph is a graph made up of bars of rectangles which are of equal width and whose lengths are proportional to the quantities they represent.
features of a bar chart
The major characteristic of the bar chart is that the body of the bars must not touch each other. There must be a space or gap between one bar and another. Bar may be arranged vertically or horizontally.
Types of bar chart or bar graph
There are three major types of bar charts. These are:
- Simple bar chart
- Component b. charts and
- Multiple ba chart
Simple bar chart
Simple b chart is used when the data given are made up of only one item or component
. 
The b chart can be presented by tabulated data with evenly spaced bars, separated by gaps with the length proportional to the magnitude of the value given.
Exemplary use of a simple bar chart or bar graph
The table represents the quantity of cocoa production in Nigeria between 1960 and 1967. Represent the information or data by a chart.
Table (a): Cocoa production in Nigeria between 1960 and 1967.
| Year | Cocoa production (Tons) |
| 1960 1961 1962 1963 1964 1965 1966 1967 | 7,000 1,500 3,000 6,000 8,500 5,000 4,000 3,500 |
Solution
Table (a): Cocoa production in Nigeria between 1960 and 1967.
| Year | Cocoa production (Tons) |
| 1960 1961 1962 1963 1964 1965 1966 1967 | 7.0 1.5 3.0 6.0 8.5 5.0 4.0 3.5 |
- From the figures given, using the scale: 1cm: 1000 tonnes, the figures can be reduced to simple ones when they are divided by 1000.
- The new values will now be.
Useful information to be derived from using a bar graph
- The year with the highest cocoa production can be calculated. The year is 1964
- The year with the least cocoa production can also be calculated. The year is 1961.
- The total cocoa production from 1960 to 1967 can be calculated, i.e. 7,000 + 1,500 + ……… + 4, 000 + 3, 000 = 38,500
- The average or mean production can also be calculated by adding the total production (as in (iii) above) and dividing it by the number of years (8 years), i.e.
7,000 + 1, 5000 + ……. = 4,000 + 3,500
8
=38,500
8 = 4, 812.5 tons/year
(b) what are Component bar chart
A component bar is used when the data involved are of two variables.
Example
Represent the population of males and females (in millions) table in towns in Edo State in 1999
| Towns | Male (m) | Female (m) | Total (m) |
| Uromi | 80 | 60 | 140 |
| Ubiaja | 60 | 50 | 110 |
| Ekpoma | 70 | 30 | 100 |
| Irrua | 30 | 15 | 45 |
Solution
WEED AND THEIR BOTANICAL NAMES
Using a graph sheet, choose a suitable scale for the graph, e.g. 1cm represent 10 units, the graph (component chart above is then drawn. COMPONENT BAR CHARTS SHOWING THE POPULATION OF SOME TOWNS
MULTIPLE BAR CHART AND USAGE
b. Multiple bar charts: The multiple chart is used when there are about three or more variables in a given data. It has multiple bars, each of which stands for a component variable.
Example
Represent Nigeria’s export of cocoa (table 2.7) from Ibadan, Abeokuta and Akure in 1969, 1970 and 1980 by a bar chart.
Table 2.7: Nigeria’s export of cocoa from Ibadan, Abeokuta and Akure in 1960, 1970 and 1980.
| Towns | 1960(tons) | 1970(tons) | 1980(tons) |
| Ibadan | 30 | 40 | 50 |
| Abeokuta | 40 | 30 | 60 |
| Akure | 50 | 70 | 40 |
Solution using bar chart
Using a graph sheet, choose a suitable scale for the graph, e.g. 1cm to represent 1o units, the graph (a multiple chart is then drawn.
Importance of production and factors of production
Production is important because of the following:
Availability of goods and services: Production helps to ensure that goods and services are made available for use by human beings.
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