Data Processing

What Data Processing covers

Data processing is examined in Unit AS 3, Fieldwork Skills and Techniques in Geography. It covers geographical information systems, and mapping techniques, annotated sketch maps, and the graph types, triangular graphs, mean, median, mode and range, spearman's rank correlation, nearest neighbour analysis, chi-squared (A2 only), location quotient (A2 only) and developing investigative skills, and the conventions of mapping and graphical work.

The 9 subtopics

Each one has its own page. CCEA AS Geography students sit this topic in the first year.

• Geographical information systems, and mapping techniquesGeographical Information System, layer in a GIS and limitations of a GIS.Open →
• Annotated sketch maps, and the graph typesSketch map, difference between a label and an annotation and line of best fit.Open →
• Triangular graphsWhat kind of data a triangular graph takes, why the three values must total 100, how a point is read and plotted, and what the vertices and the centre each mean.Open →
• Mean, median, mode and rangeHow each average is found and what the range adds, when the mean misleads, and when the median or the mode is the only one worth using.Open →
• Spearman's rank correlationWhat the test measures and what data it needs, what the sign and the size of the coefficient each say, and how significance is read off the table provided.Open →
• Nearest neighbour analysisWhat the technique measures, the scale it produces, and what values near 0, near 1 and approaching 2.15 each say about a distribution of settlements.Open →
• Chi-squared (A2 only)Data does chi-squared need, null hypothesis in a chi-squared test and degrees of freedom in a chi-squared test.Open →
• Location quotient (A2 only)What the quotient compares, what values of exactly 1, above 1 and below 1 each tell you about a region, and why it says more than a raw employment figure.Open →
• Developing investigative skills, and the conventions of mapping and graphical workSensible order of operations when processing a data set and point of putting a frame round a map or diagram.Open →

What you need to know

Answer each one before you reveal it.

Take Data Processing further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Choropleth map vs Isoline map

  Choropleth map: shading areas according to the value of a variable within each. Isoline map: joining points of equal value with a line.

• Spearman's rank correlation vs Chi-squared

  Spearman's rank correlation: a test of how strongly two ranked variables move together. Chi-squared: a test of whether an observed distribution differs from an expected one.

• Mean vs Median

  Mean: the total divided by the number of values. Median: the middle value once they are placed in order.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is a Geographical Information System?

   Model answer

   A Geographical Information System is a computer system for capturing, storing, checking and displaying data that are tied to positions on the Earth's surface. Every item of information carries a location, so the system can combine data sets that have nothing in common except where they are, and can display, query and analyse them together as maps.

2. 2

   What is a layer in a GIS, and why is the layer structure so useful?

   Model answer

   A layer is one theme of spatially referenced information held separately from the others - one layer for rivers, one for roads, one for buildings, one for flood extent, one for population density. Because they are stored separately but share the same coordinate system, they can be switched on and off, reordered and overlaid in any combination on a base map. That lets the user build exactly the map the question needs and see relationships between themes that would be invisible on separate paper maps.

3. 3

   What can be done with a GIS that cannot be done with a paper map?

   Model answer

   The map can be interrogated: clicking a feature returns the data attached to it, and the user can search for all features meeting a condition, such as every house within a flood zone. Layers can be overlaid to find where conditions coincide, buffers of a set distance can be drawn around a road or river to find what falls inside them, and distances and areas are calculated automatically. The scale and the symbols can be changed instantly, and the underlying data can be updated without redrawing the map.

4. 4

   Give geographical examples of what a GIS is used for.

   Model answer

   Mapping flood risk by overlaying river levels, relief and property locations to identify which homes are at risk; retail planning, by combining population, income and travel time data to define a store's catchment; emergency planning, by identifying the population within a given distance of a hazard and the fastest routes to it; crime and health mapping to find clusters; and environmental monitoring, by comparing land cover layers from different dates to measure change.

5. 5

   What are the limitations of a GIS?

   Model answer

   The output is only as good as the data entered: out-of-date, inaccurate or wrongly located information produces a map that looks authoritative but is wrong, and the polish of the display can conceal that. The software and the data can be expensive and need training to use properly. It also invites the user to accept an automatically generated pattern without asking what caused it - a GIS shows where things are and where they coincide, but it does not explain the geography, and coincidence in space is not evidence of a causal link.

6. 6

   How could a GIS be used to present the results of your own fieldwork?

   Model answer

   The recorded sites can be plotted by their grid references onto a base map, with each site carrying its measurements as attributes so that clicking a site shows its data. Values can then be displayed as proportional symbols, shaded areas or an isoline surface, and layers such as land use, relief or the census can be added underneath to set the results in context. Photographs and field sketches can be attached to their sampling points, and successive dates can be held as separate layers to show change.

What is inside Levo

Six ways to work the same material.

Data Processing revision questions

Is Data Processing examined at AS in CCEA Geography?

Yes. It sits in Unit AS 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.

What does Data Processing cover in CCEA AS-Level Geography?

9 subtopics: geographical information systems, and mapping techniques, annotated sketch maps, and the graph types, triangular graphs, mean, median, mode and range, spearman's rank correlation, nearest neighbour analysis, chi-squared (a2 only), location quotient (a2 only) and developing investigative skills, and the conventions of mapping and graphical work. Each one has its own page with questions and model answers.

How is Data Processing organised?

By the CCEA 3910 specification, subtopic by subtopic, so it matches the order you are taught it in.