Statistics Flashcards
What is qualitative data?
Non-numerical values.
What is quantitative data
Numerical values.
What is quota sampling?
The population is divided into groups based on a characteristic A quota is then set in each group.
What are advantages of quota sampling?
- small sample is still representative
- quick, easy, cheap
- allows for easy comparison.
- no sampling frame required
What are disadvantages of quota sampling?
- Non-responses aren’t recorded
- non-random sampling can introduce bias
- Population must be divided into groups.
What is opportunistic sampling?
A sample taken from people who are available at the time and meet the criteria.
What are advantages of opportunistic sampling?
- easy to carry out
- inexpensive
What I disadvantages of opportunistic sampling?
- Unlikely to provide a representative sample
- highly dependent on individual researcher.
What is a census?
Measuring every member of the population.
What are advantages of a census?
Completely accurate results.
What I disadvantages of a census?
- Expensive
- time consuming
- hard to process large quantities of data
- destroys the item
What is a sample?
Measuring a part of a population.
What are advantages of a sample?
- Less time consuming
- cheaper
- fewer people have to respond.
What are disadvantages of a sample?
- May be too small
- data may be inaccurate.
What is simple random sampling?
Every sample has an equal chance of being selected.
What are advantages of simple random sampling?
- Free of bias
- easy and cheap for small populations.
What are disadvantages of simple random sampling?
- Not suitable for large populations
- sampling frame needed.
What is systematic sampling?
The elements are chosen at regular intervals from an ordered list.
What are advantages of systematic sampling?
- Quick and simple
- suitable for a large populations.
What are disadvantages of systematic sampling?
- Sampling frame needed
- could introduce bias if not random.
What is stratified sampling?
The proportion of each strata is the same.
Were advantages of stratified sampling?
- accurate
- proportional to the population size.
What are disadvantages of stratified sampling?
- Population must be in distinct stratas
- sampling frame needed.
What periods of time is the large data set from?
- May - October 1987
- May - October 2015
What weather stations are included in the large data set?
- Camborne
- Hurn
- Heathrow
- Leeming
- Leuchars
- Jacksonville
- Perth
- Beijing.
What variables are recorded in the large data set?
- Daily mean temperature
- daily total rainfall
- daily total sunshine
- daily mean wind direction and wind speed
- daily maximum gust
- daily maximum relative humidity
- daily mean cloud cover
- daily mean visibility
- daily mean pressure.
What is daily mean temperature?
The average of the hourly temperature readings during the 24 hour period
What is temperature measured in?
Degrees Celsius.
What is daily total rainfall measured in?
mm
What is daily total sunshine recorded in?
to the nearest 1/10 of an hour
What is daily mean wind speed and direction record in?
knots
What is daily maximum gust measured in?
Knots
What is daily maximum relative humidity measured in?
A percentage.
If the relative humidity is above 95%, what would the weather be like?
Misty and foggy conditions.
What is daily mean cloud cover measured in?
Octas
What is daily mean visibility measured in?
Decametres.
What is daily mean pressure measured in?
Hectopascals.
what is the equation for independant events
P(A) X P(B) = P(A union B)
