Maths - Statistics

• The daily mean temperature is recorded by thermometers in a louvred screen, 1.25m above short grass or at climate data logger stations at rooftop exposure.
• Daily mean temperature is measured in degrees Celsius between 0900-0900 GMT
• Daily total rainfall is measured over a 24 hour period starting at 0900 Greenwich time. It includes melted solid precipitation. A trace or tr is an amount less than 0.05mm
• Daily total sunshine is measured using an instrument that measures the amount of solar radiation at Met Office stations. It is recorded in hours and shows the amount of bright sunshine recorded.
• Daily maximum relative humidity is a measure of how close the air is to being saturated with water Vapour. Values above 95% are associated with mist/fog
• Windspeed is measured in knots. Where 1 knot = 1.15 miles per hour. The daily mean wind speed is measured over 24 hours starting at 0000 GMT
• Maximum gust is the maximum wind speed that has occurred during the last 24 hours from 0000GMT
• Daily mean wind direction is the average over 24 hours from 0000GMT rounded to the nearest 10 degrees
• Direction of maximum gust is the direction the wind was blowing when the maximum gust occurred. Measured from true north.
• Cloud cover is measured in oktas (eighths) and is a fraction of the celestial dome that is covered by cloud.
• Visibility is the greatest distance at which a object can be seen and recognised in daylight. It is measured using of visiometer horizontally in decametres.
• Pressure is measured as the mean sea level pressure that has been calculated from measuremenets at station level. It is measured in pascals.
• The 3 overseas locations are B eijing, J acksonville and P erth.
• The 5 UK locations are C amborne H eathrow H urn L eeming L euchars
• Jacksonville is located in Florida USA close to the sea. It is in the northern hemisphere. it experiences higher temperatures and more rainfall than the UK with moderate wind speeds.
• Beijing is located in china in the northern hemisphere. It has temperatures similar to Jacksonville but a lower average temperature.
• Perth is located in australia in the southern hemisphere. The seasons are reversed so June-august is winter. It is next to the sea so experiences high wind speeds.
• A census measures every member of a population.

  benefit - accurate results

  disadvantage - expensive / time consuming
• Sampling units are individuals of a population
• Sampling frames are lists of sampling units
• In Simple random sampling there is the same chance of being selected.

  benefit - bias free

  disadvantage - need sampling frame
• In systematic sampling you take every Kth unit K= pop/sam.

  benefit - quick to use

  disadvantage - need sample frame
• In Stratified sampling the sample represents groups of a population. Sample/population x strata Then pick a random technique.

  advantage - reflects population

  disadvantage - population must be classified into strata
• In quota sampling the groups are filled by the researcher.

  advantage - no sampling frame

  disadvantage - bias
• In opportunity sampling the quota is filled by those available at the time

  advantage - easy to do

  disadvantage - unlikely to be representative
• Qualitative data is words
• Quantitative data is numerical
• Continuous data can take any value
• Discrete data has definite values