### Chap 16: Summary - Purpose of Different Types of Graphs

Pictogram:
• It is visually appealing
• It is easy to read, especially when each picture represents a frequency of one
• It is hard to represent exact quantity using pictures that are partially drawn
• The pictures must be of consistent size for fair comparison among the categories
• It is best for data which do not have many categories
Bar Graph/ Column Graph:
• It can display data with many categories
• It is easy to identify the category with the highest frequency from a bar graph
• It is convenient and easy to compare two or more sets of data with many categories
• Bar graphs should always start with zero on the frequency axis or it can give false impressions when we make comparison of different bars
Pie Chart:
• It can display a data set with many categories in terms of numbers or percents
• It can display the relative proportions of different categories in a data set
• The 'whole' pie should have a meaningful interpretation, i.e. the different categories of the data should represent parts of a whole
• It is not easy to compare two pie charts
• Due to rounding of quantities, the total may not give 100%
Line Graph:
• It can display patterns and trends over time better than most other graphs
• It can compare the trend of two or more data sets easily
• Intermediate values can be readily estimated from the graph
• Intermediate values can be easily obtained but they may not be meaningful depending on the contet
• The comparison of two line graphs can sometimes lead to misinterpretation when the scales used for the (vertical) axis are different
Source: New Express Mathematics 1 Chapter 13