Large Data Set (Edexcel AS Maths) : Revision Note

Using a Large Data Set

What is a large data set?

• As part of your course there is a large data set that you can use

• It contains lots of information

• You are not expected to memorise any results from the data

• You will have an advantage if you are familiar with the large data set

  • Understand what the variables are

  • Understand the terminology used

  • Understand the context

• You will not get a copy of the large data set in your exam

  • if you are required to calculate anything using the large data set you will be given an extract within the question

What skills can I practice with a large data set?

• Cleaning data

  • There might be missing data

  • You could identify outliers and question their validity

• Sampling and hypothesis testing

  • You can practice different methods of sampling using the data

  • You could use a sample to test a hypothesis

• Statistical measures and diagram

  • You could calculate summary statistics for different variables

  • You could create different diagrams

  • You can interpret the summary statistics and diagrams (as it is real data you could explore the context behind the results)

  • You could compare summary statistics and diagrams

Do I have to use spreadsheets and other technology?

• You will not be assessed on using spreadsheets

  • However, it is a useful skill for your future career

• You could use technology to calculate the summary statistics and create the statistical diagrams

  • This will help you to practice these skills whilst using real data

  • Spreadsheets can calculate summary statistics

  • In the exam you could use the statistics mode on your calculator

Summary of the Edexcel Large Data Set

What is the data about?

• The data consists of samples of data on the weather for eight locations over two different time periods

• The five UK locations are:

  • Leuchars: town in Scotland

  • Leeming: village in North Yorkshire

  • Heathrow: hamlet in Greater London

  • Hurn: village in Dorest (South West England)

  • Camborne: town in Cornwall (South West England)

• The three international locations are:

  • Beijing: capital city of China

  • Perth: capital city of Western Australia (state of Australia)

  • Jacksonville: city in Florida (state of USA)

• The two time periods are:

  • May to October 1987

  • May to October 2015

What variables are included in the large data set?

• Daily mean (air) temperature

  • Measured in degrees Celsius (°C) given to 1dp

  • Average of hourly temperature readings between 0900 - 0900 GMT

• Daily total rainfall

  • Measured in millimetres (mm) given to 1dp

  • Measured for the 24 hours starting at 0900 GMT

  • A trace of rain 'tr' is an amount less than 0.05mm

• Daily total sunshine

  • Measured in hours (hr) given to 1dp

• Daily maximum relative humidity

  • Given as a percentage given to the nearest integer

  • A reading above 95% is associated with mist and fog

• Daily mean windspeed and direction

  • Mean measured in knots (1 kn = 1.15 mph) given to nearest integer and is described using the Beaufort conversion (calm, light, etc)

  • Direction measured in degrees rounded to the nearest 10 and is given as a cardinal direction (north, south, etc)

  • Averaged for 24 hours starting at 0000 GMT

• Daily maximum gust and direction

  • Measured using the same units as windspeed

  • The maximum instantaneous speed over the 24 hours

• Cloud cover

  • Measured in Oktas (eighths of the sky covered by cloud)

• Daily mean visibility

  • Measured in decametres (1 Dm = 10 m) horizontally

• Daily mean pressure

  • Measured in hectopascals (1 hPa = 100 Pa = 1 millibar)

Is the data complete?

• There are missing or unknown pieces of data

  • These are listed as 'n/a' or '-'

  • The total daily total sunshine, mean windspeed and maximum gust is unknown for the first half of May 1987 for the UK cities

  • The data should be cleaned before samples are taken

• The three international cities only contain data for:

  • Daily mean temperature, daily total rainfall, daily mean pressure and daily mean windspeed

What are some of the important features?

• Consider which locations are closer to the equator

• Consider which locations are near a coast

  • Jacksonville, Perth, Camborne, Hurn, Leuchars are near the coast

• Consider which locations are in each hemisphere

  • Perth is in the southern hemisphere so have winter when UK has summer

• Consider which variables are discrete and which are continuous

  • Cloud cover is discrete

• You can use 0 or 0.025 for rainfall that is listed as 'tr'

• The great storm of 1987 happened 15-16 October in UK

  • The wind speeds were high at this time

  • The south and south-east of England was affected

  • This will skew some variables (wind/gust/rainfall)

  • This won't have much impact some variables (sunshine/cloud cover)

    • October in the UK is normally cloudy and has less sunshine

  • Don't worry about remembering the exact dates of this but it is something to be aware of

• Consider the number of days in each month

  • 30 days in June and September

  • 31 days in May, July, August and October

  • In total the LDS covers 184 days