1. Data collection Flashcards
What are the advantages and disadvantages of a census?
Completely accurate result Time consuming Expensive Can't be used when it is destroying the thing it is investigating Hard to process large amounts of data
What are the advantages and disadvantages of a sample?
Less time consuming
Less expensive
May not be accurate
May not represent sub groups
What are the three types of sampling?
Simple random: everyone has an equal chance of being selected
Systematic: every kth member of the population
Stratified: random samples are taken from the subgroups which you want represented where the sample size is ratio of the subgroups size relative to the population
What are the positives and negatives of random sampling?
Free of bias
Easy and cheap
Not suitable when the population or sample size is large
Sampling frame is needed
What are the two types of non-random sampling?
Quota sampling: researcher selects a sample that reflects the characteristics of the whole population
Opportunity sampling: consists of taking the sample from people who are available
What are the positives and negatives of quota sampling?
Small sample can be representative
No sampling frame required
Quick, easy and inexpensive
Allows for an easy comparison between different groups
Can introduce bias
Dividing into groups can be costly/innacurate
Increasing scope increases the expense and time needed
What are the positives and negatives of systematic sampling?
Simple and quick to use
Suitable for large samples or populations
Sampling frame is needed
Bias can be introduced if the sampling frame is not random
What are the positives and negatives of stratified sampling?
Sample accurately reflects the population structure
Guarentees proportional representation
Population must clearly be classified into distinct strata
Selection within each stratum suffers from the same issues as random sampling
What are the positives and negatives of opportunity sampling?
Easy to carry out
Inexpensive
Unlikely to produce a representative sample
Highly dependent on the researcher
What are the types of data?
Quantitative: numerical data
Qualitative: non-numerical data
Continuous: data that can take any value in a given range
Discrete: data that can only take specific values
What is daily mean temperature in reference to the large data set?
The average hourly temperature readings during a 24-hour period
Measured in degrees celcius
What is daily total rainfall in reference to the large data set?
All precipitation, including solid precipitation melted before taking any measurements
Amounts less than 0.05mm are recorded as trace
What is daily total sunshine in reference to the large data set?
Amount of solar radiation
Recorded to the nearest tenth of an hour
What is daily mean wind direction and windspeed in reference to the large data set?
Averaged over 24 hours from midnight to midnight
Mean wind directions are given as bearings and compass directions
Measures in knots: nautical miles per hour
Data for mean windspeed is categorised according to the Beaufort scale
What is daily maximum gust in reference to the large data set?
Highest instantaneous windspeed recorded
Direction is also recorded
Measured in knots
What is daily maximum relative humidity in reference to the large data set?
Percentage of air saturation with water vapour
Relative humidities above 95% give mist or fog
What is daily mean cloud cover in reference to the large data set?
Oktas (eighths of the sky) covered by cloud
What is daily mean visibility in reference to the large data set?
Greatest horizontal distance at which an object can be seen in daylight
Measured in decametres (Dm)
What is daily mean pressure in reference to the large data set?
Measures in hectopascals (hPa)
What is a sample?
A subset of the population
What is a population?
The set of things that you are interested in
What is a census?
A collection every data point in the population
What is a sampling frame?
A list of sampling units
What are the UK locations of the large data set?
Leuchars: in Scotland Leeming: middle of the country Heathrow: below London Hurn: bottom middle Camborne: very bottom left
What are the non-UK locations in the large data set?
Jacksonville: above the equator, below Beijing, above Florida
Perth: below the equator, bottom left of Australia
Beijing: highest location
What are the categories included in overseas locations?
Daily mean temperature
Daily total rainfall
Daily mean pressure
Daily mean wind speed
Is Beijing or Perth further west?
Beijing
What are the UK locations in terms of north to south?
Leuchars Leeming Heathrow Hurn Camborne
What are the UK locations in terms of West to east?
Camborne Leuchars Hurn Leeming Heathrow
What dates are included in the large data set?
May to October 1987
May to October 2015
