Unit 2: Geographical Skills Ed Fairburn, artist 

Reminder! An overview of Unit 2 Worth 30% of your AS 1 hour exam on Friday 15th May Total of 50 marks Questions on skills (part 1) and your fieldwork investigation (part 2) You will need the following equipment in the exam: Rubber Ruler Protractor Compasses Calculator

Graphical skills In the next few lessons we will cover the following graphical skills: Line graphs: simple, comparative, compound and divergent Pie charts Proportional divided circles Triangular graphs Radial diagrams

Line graphs Line graphs are used to show continuous data. Simple line graphs are used for showing the relationship between two variables. One of these variables is usually time but they can also show other factors. For example, the relationship between temperature and altitude.

Two or more sets of data to compare Line graphs Comparative Two or more sets of data to compare

Shows different proportions of the total. Line graphs Compound Shows different proportions of the total. Location based services

Also when a graph displays positive and negative values. Line graphs Divergent These are used when one set of data is provided for part of the period under consideration and then this data set is split into separate components for another part of the period. Divergent Also when a graph displays positive and negative values.

Line graph activity Go to the June 2010 paper in your exam question booklet: Answer Qu. 1 (a) (i) Answer Qu. 1 (a) (ii)

Pros and cons Pros Cons It is easy to read. A broken scale can be used when the data starts at a large number.  Shows specific values of data. Shows patterns in data clearly, meaning that they visibly show how one variable is affected by the other as it increases or decreases. Enable the viewer to make predictions about the results of data. You can change the way the data of a line graph appears, by not using consistent scales on the axis. Used with continuous data only. Unsuitable if there are only a few data points.

Pie charts Pie charts are used to show how something is divided into shares or percentages of a whole. The pie chart is useful to show the total data divided into proportions. It often has good visual impact but it can be difficult to read the data accurately, particularly if there are several categories. The segments should be drawn from the largest first and the smallest last unless there is an "others" category in which case that should be last regardless of its size. Segments should be shaded in different colours and a suitable key or labels added. The raw data and percentage figures can be added to the key if appropriate.

Proportional pie charts Proportional pies use the concepts of pie graphs and proportional symbols together. The diameter of each pie is proportional to the total. This method integrates data together and involves a spatial element when plotted on a suitable base map.

Do you remember how to draw pie graphs? Pie chart activity Go to the June 2010 paper in your exam question booklet: Answer Qu. 1 (b) (i) Answer Qu. 1 (b) (ii) Do you remember how to draw pie graphs?

Can you think of any more? Pros and cons Pros Cons Displays relative proportions of multiple classes of data size of the circle Can be made proportional to the total quantity it represents Summarises a large data set in visual form Visually simpler than other types of graphs Permits a visual check of the reasonableness or accuracy of calculations Requires minimal additional explanation Easily understood due to widespread use in business and the media Does not easily reveal exact values Many pie charts may be needed to show changes over time Fails to reveal key assumptions, causes, effects, or patterns Easily manipulated to yield false impressions Can you think of any more?

Graphical skills In the next few lessons we will cover the following graphical skills: Line graphs: simple, comparative, compound and divergent  Pie charts  Proportional divided circles  Triangular graphs Radial diagrams

Triangular graphs have three axes. They are used to show data which is in percentage form, where each 100% is divided into three variables. Once the graph is completed, the variation between the different sets of data can easily be seen. E.g. Percentage of a country’s workforce employed in primary, secondary and tertiary industry.

Triangular graphs: step-by-step Label the axis with the three % variables: Primary Secondary Tertiary Primary Tertiary Secondary

If you can’t remember the direction, just check with a protractor! You will plot the three sets of data using each axis… you must follow the line in the correct ‘direction’! Data should always be plotted at a 60° angle. Use a protractor to work it out… place it on the ‘0’ of each axis and follow the 60° line. If you can’t remember the direction, just check with a protractor! Primary Secondary Tertiary

Primary Primary Tertiary Tertiary Secondary Secondary County A Country B Country C Primary 60 50 31 Secondary 10 35 14 Tertiary 30 15 55 Primary Secondary Tertiary Primary Secondary Tertiary

Primary Primary Tertiary Tertiary Secondary Secondary County A Country B Country C Primary 60 50 31 Secondary 10 35 14 Tertiary 30 15 55 Primary Secondary Tertiary Primary Secondary Tertiary

What does the graph show? County A Country B Country C Primary 60 50 31 Secondary 10 35 14 Tertiary 30 15 55 What does the graph show? Primary Secondary Tertiary Primary Secondary Tertiary

Pros and cons Pros Cons Clearly displays the proportional balance between 3 variables. The change in the 3 variables over time can be seen if variables are plotted for different times. Several sets of data can be plotted on one graph. Clear visual impression of the dominant variable. Summarises data for a large group set much more effectively than in many bar or pie charts. Points which have similar characteristics are located in clusters on the graph so they can then be classified. Only 3 variables can be plotted. Figures must be in the form of percentages. Can you think of any more? Figures must add up to 100%

Triangular graph activities Complete the ‘type of service’ worksheet. Plot a few of the countries on the ‘workforce’ worksheet.

Kite diagram Kite diagrams are used to see trends in statistics in a visual way. These show the change of a percentage over distance. The central line for each diagram has a value of 0. The ‘kite’ is then drawn symmetrically both above and below the line to represent your data. For example, you can use kite diagrams to compare the distribution of plant species along a coastline.

Kite diagram activity Complete the kite diagram worksheet

Pros and cons Pros Cons Visually shows increases and decreases in the vegetation cover. Values can be read off of the graph. Effective way of representing percentages. Show abundance, species distribution and diversity at certain points. Limited amount of data that can be plotted using them. They have a very limited use, usually only for plant succession. Values often need to be rounded to be plotted on the kite diagram which means the data loses its accuracy, especially if many different species are on the diagram as this makes each line for the species quite small. Could be difficult for people to interpret if they don’t know about kite diagrams. Only a small number of species can be represented otherwise the diagram becomes quite large. Assumptions are made about the presence and absence of species between the points that were measured.

Radial (rose) diagram Radial diagrams are a type of graph where values extend out from a central point; therefore they show the relationship of each variable to the central point/item. They are particularly useful when one variable is directional and uses the points of a compass, or cyclical (e.g. time). Often used to show flow of people or traffic over a period of time, in which the circle represents a clock face.

Pros and cons Pros Cons They are advantageous because trends in the data set are clearly shown, with the variable with the largest value being highlighted on the graph. The data that is applicable to this method is limited. It can also be hard to read exact values from the scale on the axis, as it often makes the diagram too crowded to include the scale. Data often has a wide range of values when plotting a number of different variables, meaning that it can be hard to find a suitable scale to use.