Stats Chapter 1 Flashcards
Population
The whole set of items that are of interest
Census
Observes or measures every member of a population
Sample
A subset of the population which is used to find out information about the population as a whole
Sampling units
Individual units of a population
Sampling frame
A list of individually named or numbered sampling units
Random sample of size n
A sample in which every sample of size n has an equal chance of being selected
Use random number generator and sampling frame or lottery sampling (hat)
Systematic sampling
Individuals are chosen at regular intervals from an ordered list, the first person chosen is random
Stratified sampling
Population is divided into mutually exclusive strata (eg males females) and a random sample is taken from each
Quota sampling
Splitting the population into groups and sampling a given number of people from each group, a group is chosen that reflects the whole population
Opportunity/ convenience sampling
Sample taken from people who are available at the time when the study is being carried out and who fit the criteria you are looking for (first come first serve)
Quantitative data/variables
Variables or data associated with numerical observations
Qualitative variables/data
Variables or data associated with non-numerical observations
Continuous variable
A variable that can take any value in a given range
Discrete variable
A variable that can only take specific values in a given range
Class boundaries
The maximum and minimum values in each class
Midpoint
Average of the class boundaries
Class width
Difference between the upper and lower class boundaries
Daily mean temp
Average of hourly temp readings in 24 hours
Daily total rainfall
All precipitation, including snow and hail, amounts less than 0.05mm are trace or tr
Daily total sunshine
Recorded to nearest tenth of an hour
Daily mean wind direction and windspeed
in knots, averaged over 24 hours. Mean wind directions given as bearings. Windspeed given usen Beaufort scale
Daily maximum gust
Highest instantaneous windspeed recorded, direction from which it blew is also recorded
Daily maximum relative humidity
Percentage of air saturation with water vapour, above 95% gives foggy or misty conditions
Daily mean cloud cover
measured in ‘oktas’ or eights of sky covered by cloud
Daily mean visibility
Greatest horizontal distance at which an object can be seen in daylight, measured in Decametres
Daily mean pressure
Measured in hectopascals
