 A bar graph is a pictorial rendition of statistical data in which the independent variable can attain only certain discrete values. The dependent variable may be discrete or continuous. The most common form of bar graph is the vertical bar graph, also called a column graph.

In a vertical bar graph, values of the independent variable are plotted along a horizontal axis from left to right. Function values are shown as shaded or colored vertical bars of equal thickness extending upward from the horizontal axis to various heights.

In a horizontal bar graph, the independent variable is plotted along a vertical axis from the bottom up. Values of the function are shown as shaded or colored horizontal bars of equal thickness extending toward the right, with their left ends vertically aligned.

## properties of bar graph

here are properties of bar graph which make them unique

• the rectangular bar can be drawn horizontally or vertically
• the height of the rectangular bar is equivalent to the data they represent
• the rectangular bars must be on the common base
• all rectangular bars should have equal width and should have equal space between them

## steps of drawing the bar graph

• take a graph paper and give title of the bar graph e.g most popular cities
• draw the horizontal axis (x-axis) and the vertical axis (y-axis) on the plane
• lebel the horizontal axis as name of the the city which is an independent variable and veritical axis as population size which is dependent variable
• lebel the cities names such as dubai, tokyo, calfornia and give an equal gap or leave an equal space between each city on the horizontal axis
• give the scale range on the vertical axis for the given data like 100,200,300,400,500
• start making rectangular bars with equal gapsfor each city and give height to their respective population
• the bar graph is ready, observe the height of the rectangular bars of each city and find the most populated city

while drawing bar graph it is very important to mention four things- lebels on the axes, title, scale and name of the axes

## types of bar graphs

bar graph are mainly classified into types

• vertical bar graph
• horizontal bar graph

apart from vertical and horizontal bar graph, there are two more types of bar graph namely; grouped bar graph and stacked pr compound bar graph

## The following are advantages of bar graph:

• Show each data category in a frequency distribution

• Display relative numbers or proportions of multiple categories
• Summarize a large amount of data in a visual, easily interpretable form
• Make trends easier to highlight than tables do
• it helps in studying patterns over long period of time
• it is used to compare data sets. data sets are independent of each other
• most widely used method of data representation. therefore, it is used by various industries
• Estimates can be made quickly and accurately
• Permit visual guidance on accuracy and reasonableness of calculations
• Accessible to a wide audience
• can easily compare two or three data sets

## The following are Disadvantages of bar graph:

• fail to expose key assumptions, causes, impacts and patterns
• can be easily manipulated to give false impressions
• do not show inter relationship between activities
• managing projects becomes difficult without those relationship between activities
• it is difficult to judge the impact of unexpected events on the rest of the construction process
• use only discrete data