Statistics Year 1 Unit 1 Flashcards
Define population
A complete set of data where every element is included
Define sample
A selection of the population
Define census, why is it rare?
Every element is surveyed, rare because it is expensive and labor-intensive
Define sampling units
These are the elements of data in a sample
Define sampling frame
A list of sampling units
Define random sampling methods
Every element of the population has an equal chance of being selected
What are the 3 random sampling methods?
Simple random sample, systematic sample and stratified sampling
Define simple random sample
using random numbers or ‘names out of a hat’
Define systematic sample
all elements numbered, the first element is chosen randomly then every nth element is chosen
Define stratified sampling
The proportion of groups in the population are represented in the survey
What is the danger of non-random sampling?
bias
Define opportunity sampling
Your sample is whoever turns up
Define quota sampling
Numbers are calculated for each group then when groups are filled, others are ignored
Define qualitative data with examples
Groups of data, non numerical, qualities like colours
Define quantitative data with examples
Numerical data, quantities like temperature
What two types of data can quantitative data be sectioned into?
Discrete and continuous
What is discrete data?
Whole numbers, can’t be decimals, like when you’re counting something
What is continuous data?
Data that can take any value, including decimals, for example, height, it can continue between each whole number of kilograms
What does n/a mean?
Not availioble, used when the data needed is not availible
If one cell of data has n/a in it, what should you do to the whole row?
Ignore it
What does tr mean?
Trace, there was some but not enough to provide a reading and more than 0
If a cell of data has tr in it, what should you do to it? Why?
Change it to 0 so it can be included in means and other calculations
How is daily mean temperture measured?
Values are noted in degrees (celcius) and tenths, values below 0 are preceded by a minus sign
What is the daily mean temperature?
The average of the hourly air temperature readings during the period 0900-0900 GMT
How is daily total rainfall measured?
millimetres (mm)
What is daily total rainfall?
24 hour periods commencing at 0900 GMT on the day of entry and includes any solid precipitation, such as snow or hail, which is melted and measured in the same way as rainfall
How is daily total sunshine measured?
In hours and tenths
What is daily total sunshine?
The amount of bright sunshine recorded on the day of entry, measured by an instrument that measures the amount of solar radiation exceding a threshold
How is daily maximum relative humidity measuered?
As a percentage
What is daily maximum relative humidity?
A measure of how close the air is to being saturated with water vapour. Values greater than 95% are associtated with mist and fog
How is wind speed measured?
Knots
What is knots to mph?
1 knot = 1.15 mph
How is the daily mean wind speed measured?
Averaged over the 24 hours from 0000GMT on the date given
What is maximum gust speed?
The maximum instantaneous speed that occured during the 24 hours from 0000GMT on the date given
How is the daily mean wind direction measured?
Averaged over the 24 hours from 0000GMT on the date given, averaged to the nearest 10 degrees
How is daily maximum gust direction measured?
in degrees from true north
What is daily maximum gust direction?
The direction from which the wind was blowing when the maximum gust during the hour commencing at the time of entry occured
What is cloud cover?
The fraction of the celestial dome coverd by cloud
How is cloud cover measured?
Measured in eigths (Oktas)
What is visibility?
The greatest distance at which an object can be seen and recognized in daylight, or at night could be seen and recognized if the general illumination was raised to daylight level.
How is visibility measured?
Measured horizontally, values noted in decametres (Dm), a dash indicates data not available
How is pressure measured?
By the SI unit of pressure, the pascal (Pa)
Which station is the furthest north?
Leuchars
Which station is the furthest south?
Perth
Describe where Leuchars is
A coastal station far north in Scotland
Describe where Leeming is
An inland station in Northern England
Describe where Heathrow is
An inland station in Southern England
Describe where Hurn is
A coastal station in Southern England
Describe where Camborne is
A Coastal station in South West England
Describe where Jacksonville is
An overseas Coastal station in South East USA
Describe where Perth is
An overseas coastal station in South West Australia
Describe where Beijing is
An overseas inland station in Eastern China
