University of Bristol
Wellcome Trust
Recommended by:
Society of Biology
PEEP for Physics & Ethics at GCSE
 

Graphs and Charts



Click to enlarge

 

How fast does a tropical coral like this grow? Warm water reefs grow at up to 150 mm a year, however scientists are arguing that increasing levels of carbon dioxide in the oceans is slowing the rate of coral growth.

 

Line graphs can be used to show a trend or a rate of change like this but you need to interpret them carefully. What’s the difference between the two graphs on the right? Which is more helpful? To whom? 

Pie charts are used to show proportions or percentages represented as slices of a pie. The bigger the slice of pie the more that slice represents. Here a pie chart is used by the US National Center for Chronic Disease Prevention and Health Promotion to represent the national figures for the success of assisted reproductive technologies in 2001.
 


Click to enlarge
 


But pie charts aren’t very good when displaying small chances or risks. In the fictitious example left, the risk of a serious complication is double that of an allergic reaction but it is hard to pick out.

 

 

The same thing happens with a bar chart. Bar charts are used for comparing the total number of events or occurrences in different categories.


Click to enlarge
 


Risks involved in a new
treatment for diabetes
Click to enlarge

One way around this is to use a ‘wall of balls’. People find them much easier to interpret.

 

 

 

 Probability and chance

 

What's your opinion?

Average rating

Not yet rated

Read comments

speech bubble  No comments yet. Why not be the first person to add one?

Bookmark this pagefacebook myspace bebo delicious diigo stumbleupon twitter reddit yahoo google