Data Presentation (Edexcel IGCSE Geography)

Data Presentation

• There are different types of data
• Quantitative and qualitative
• Continuous and discrete
• There are many ways in which data can be presented
• Graphs
• Annotated photographs
• Field sketches 
• Maps
• Diagrams
• The types of data presentation used will depend on the data collected

Graphical Skills

• Much of the data collected will be presented in the form of graphs of some form
• Each type of graph is suitable for particular data sets
• The graphs also may have advantages and disadvantages

Bar graphs 

• One of the simplest methods to display discrete data 
• Bar graphs are useful for:
  • Comparing classes or groups of data
  • Changes over time

Strengths	Limitations
Summarises a large set of data	Requires additional information
Easy to interpret and construct	Does not show causes, effects or patterns
Shows trends clearly	Can only be used with discrete data

Bar Graph Showing Cross-Sectional Area Sites 1-6

Compound or Divided Bar Chart

• The bars are subdivided to show the information with all bars totaling 100%
• The main use of a divided bar chart is to compare numeric values between levels of a variable such as time

Population Pyramid

• A type of histogram
• Used to show the age-sex of a population
• Can be used to show the structure of an area/country
• Patterns are easy to identify

Line Graphs 

• One of the simplest ways to display continuous data
• Both axes are numerical and continuous 
• Used to show changes over time or space

Strengths	Limitations
Shows trends and patterns clearly	Does not show causes or effects
Quicker and easier to construct than a bar graph	Can be misleading if the scales on the axis are altered
Easy to interpret	If there are multiple lines on a graph it can be confusing
Requires little written explanation

• A river cross-section is a particular form of line graph because it is not continuous data but the plots can be joined to show the shape of the river channel

Line Graph to show a Cross-section of the River Channel

Pie Chart

• Used to show proportions, the area of the circle segment represents the proportion
• A pie chart can also be drawn as a proportional circle 
• Pie charts can be located on maps to show variations at different sample sites

Strengths	Limitations
Clearly shows the proportion of the whole	Do not show changes over time
Easy to compare different components	Difficult to understand without clear labelling
Easy to label	Hard to compare two sets of data
Information can be highlighted by separating segments	Can only be used for a small number of categories otherwise lots of segments become confusing

Pie Chart Showing Energy Sources in an area

Rose Diagrams

• Use multidirectional axes to plot data with bars
• Compass points are used for the axes' direction
• Can be used for data such as wind direction, noise or light levels

Wind Direction Shown on a Rose Diagram

Triangular Graphs

• Have axes on three sides all of which go from 0-100
• Used to display data which can be divided into three
• The data must be in percentages 
• Can be used to plot data such as soil content, employment in economic activities

Triangular Graph Showing Components of Soil Samples at Different Sites

Scatter graph

• Points should not be connected
• The best-fit line can be added to show the relations
• Used to show the relationship between two variables
  • In a river study, they are used to show the relationship between different river characteristics such as the relationship between the width and depth of the river channel

Strengths	Limitations
Clearly shows data correlation	Data points cannot be labeled
Shows the spread of data	Too many data points can make it difficult to read
Makes it easy to identify anomalies and outliers	Can only show the relationship between two sets of data

Scatter graph to show the Relationship Between Width and Depth on a River Long Profile

Choropleth Map

• Maps which are shaded according to a pre-arranged key
• Each shade represents a range of values
• It is common for one colour in different shades to be used
• Can be used for a range of data such as annual precipitation, population density, income levels, etc...

Strengths	Limitations
The clear visual impression of the changes over space	Makes it seem as if there is an abrupt change in the boundary
Shows a large amount of data	Distinguishing between shades can be difficult
Groupings are flexible	Variations within the value set are not visible

Choropleth Map Showing Variations in Income in London

Proportional Symbols Map

• The symbols on the map are drawn in proportion to the variable represented
• Usually, a circle or square is used but it could be an image
• Can be used to show a range of data, for example, population, wind farms and electricity they generate, traffic or pedestrian flows

Strengths	Limitations
Illustrates the differences between many places	Not easy to calculate the actual value
Easy to read	Time-consuming to construct
Data is specific to particular locations	Positioning on a map may be difficult, particularly with larger symbols

Proportional Circles Map Showing GDP (Billion US$) across Europe

Photographs 

• Photographs can be taken to show different aspects of sample sites 
• These can be annotated as part of the fieldwork analysis

Strengths	Limitations
An accurate record of the time	Not all photographs are relevant
Can represent things more clearly than numerical data	Can be subjective and biased as the student selects what is photographed
Can be used to show data-collection techniques	Photographs sometimes contain too much information
Can be used next to historical photographs to show changes over time	They are two dimensional so judging depth is difficult
Helps recall key features

Field Sketches

• Should include location/site number, title and compass direction
• Includes the key features at a site 

Strengths	Limitations
Things can be left out of the sketch if they are not relevant to the enquiry	The scale in the sketch may be inaccurate
Smaller important areas can be more detailed	Important details may be missed
Gives a broad overview of the features	The sketch may contain inaccuracies which affect the analysis for example more litter than there actually was at the site
Helps recall of key features

Maps

• An essential part of any fieldwork enquiry is to show the location of features and sample sites
• Maps can also be used to show relevant features such as amenities around the sample sites

Strengths	Limitations
Size and scale of features/site can be accurately measured	The map may be out of date
Key to show features around the sample sites	Maps cannot show changes over time
Allows distribution of features to be shown accurately	Bias may be introduced by highlighting certain features