# Numerical Skills

A key feature of fieldwork assessment is your ability to handle data to draw informed conclusions. Part of data handling is presentation, but this Geography quiz concentrates on the numerical skills that are required for the GCSE. These skills will be assessed in your written exams as well as in your fieldwork. It will be worth having a pen, paper and calculator handy before starting the quiz.

You need to demonstrate that you understand areas and scales and are aware of the relationships between units, a simple example of this could be the relationship between metres and kilometres or hectares and square metres. The two common map scales that you will use at GCSE are 1:50,000 and 1:25,000 - you should know that these mean that one centimetre on the map represents 50,000 cm (0.5 km) or 25,000 cm (0.25 km) on the ground. Each square on an OS map grid represents an area of one square kilometre.

When designing your fieldwork, you need to be able to design data collection sheets before you start. An example of this would be if you were studying water flow at the edge and in the centre of a stream. A suitable table would include a column for the distance from the starting point of your survey with two columns for flow rate, one for the edge and the other for the centre. Data collection sheets can be modified if you don't get them quite right, but you will be required to explain why you changed them in your evaluation. You won't lose marks but you could easily gain them for doing that. Your planning also needs to show that you appreciate ways of ensuring that your data is as accurate and reliable as possible for example, repeat readings or comparing with a control group as appropriate.

When processing numerical data, you will need to use a number of valid statistical techniques, including appropriate measures of central tendency, spread and cumulative frequency (in other words - median, mean, range, quartiles and inter-quartile range, mode and modal class). Being able to work out and use percentiles, percentage increases and percentage decreases is essential, but once you get the hang of it, it's not actually too difficult. At the highest levels, you need to be able to spot weaknesses in selective statistical presentation of data.

Finally, when processing bivariate data (that's the posh way of saying data that includes two variables), not only should you be able to identify and draw trend lines on a graph, you should be able to work out gradients and use the trend lines to describe any correlation between data sets and extrapolate and interpolate the trends you have identified. But don't get too stressed about this, you will already have done loads of this in maths and science lessons as well.

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1. Which of the following is NOT correct?
Make sure that you revise the meaning of map scales
2. Which of the following statements is NOT true?
Accuracy and reliability are not the same
3. A class was asked to prepare an isoline map showing the pedestrian flow around the CBD of their local town using 5 minute pedestrian counts. They split up and everyone made their observations at 1pm. Which of the following would be the most useful columns for putting the class results into a table?
An isoline map is designed to present bivariate data, so only two columns are needed. The time at which each count was made was the same, so it is not necessary to record it in the table of results
4. Which of the following distances are equivalent?
You need to be able to correctly convert from one SI unit to another
5. What is the mode of these numbers: 8, 7, 5, 9, 3, 5, 6, 4, 6, 6?
The mode (or modal value) is simply the number that appears in the list most frequently
6. What is the median of these numbers: 8, 7, 5, 9, 3, 5, 6, 4, 6, 6?
When there are an even number of results, the median is the mean of the two central numbers, in this case 6 and 6. It is also referred to as the 50th percentile
7. What is the range of these numbers: 8, 7, 5, 9, 3, 5, 6, 4, 6, 6?
The range is the difference between the largest and smallest number
8. On an OS map, what area would be represented by a block that measured 4 grid squares long and 3 grid squares wide?
A grid square on an OS map represents one square kilometre on the ground
9. The GDP of Bangladesh in 2014 was 173 billion US dollars. In 2015, this had increased to 195 billion US dollars. What is the approximate percentage increase?
You can forget about the units for the calculation as you are just working out a percentage. You don't need to write all of the zeros to represent the billion as they are the units. The increase in GDP is 22 (195 - 173). The original value is 173. The percentage increase is therefore 22 divided by 173 multiplied by 100 to get the percentage. This works out at 12.7 so the closest answer is 13%
10. What is the mean of these numbers: 8, 7, 5, 9, 3, 5, 6, 4, 6, 6?
The mean is also called the arithmetic mean or the average and is one measure of central tendency