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

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