Karteikarten
Statistics 1 : Data collection
Karten in diesem Stapel (17)
- 1What is a population? What is a sample?- A population is the total number of items that you are interested in
- A sample is a section of the population which is supposed to represent the entire population - 2What is a sampling frame? What is a sampling unit?- A sampling frame is the section of the population that has been taken and will be used to represent the entire population
- A sampling unit is each individual component which would be found within the sampling frame - 3What is a cencus? What are the advantages and disadvantages of using a cencus?- A cencus is data collected from the entire population
-Adv = Data is 100% accurate
Disadv = Data will be longer and harder to process fully
More time consuming and expensive
Cannot be used if it will cause testing destruction (E.g draining a fish pond to count the exact number of each fish species) - 4What are the advantages and disadvantages of using a sample?-Adv = Cheaper
Quicker
Less data to process
-Disadv = Not as accurate
Data may not be large enough to suggest a trend for the whole population? - 5What is random sampling? What is the method for random sampling?-Random sampling is when you randomly choose a certain number of individuals for the sampling, this is done to avoid bias.
-Give all the sample units within the sample frame numbers, and use a random number generator to pick the sample units that correspond to the number - 6What are the advantages and disadvantages of random sampling?- Adv = Results are free from bias
Its easy and cheap to conduct
Each number has an equal chance of being selected
-Disadv = Sample frame needed
Not suitable for large populations - 7What is systematic sampling? What is the method for systematic sampling?Systematic sampling is when you choose the sample units in intervals
-The method for this is you start from a random term from 1 - x, then from the chosen number you then add intervals to it (using the equation below)
Population size
x = (DIVIDE LINE)
Sample size - 8What are the advantages and disadvantages of systematic sampling?-Adv = Simple and quick to use
Suitable for large populations/samples
-Disadv = Sampling frame is required
Can introduce bias if the sampling frame isn't random - 9What is stratified sampling? What is the method for stratified sampling?-Stratified sampling is when data is placed into groups called strata, and a simple random sample is carried out in each group.
-The method for this is,
Sample size
(DIVIDE LINE)
Population size
This is done in each strata - 10What are the advantage and disadvantages of stratified sampling?-Adv = Reflects the population structure
Guarantees a proportionate representation of each group in the population
-Disadv = Population must be put into clearly classified strata
Selection within the strata suffer from, needing a sample frame, and they're not suitable for large populations - 11What is Quota sampling?Quota sampling is when the population is divided into groups based on characteristics. The purpose of the quota is to reflect the proportion of a groups to each others, to base an estimate for the entire population.
- 12What are the advantage and disadvantages of Quota sampling?Adv: Allows for a small sample to represent the whole population
A sample frame isnt needed
Quick easy and inexpensive
Allows for comparisons between different quotas in the population
Disadv: Can introduce bias
Dividing population into groups can make the sample inaccurate or costly - 13What is Opportunity sampling?Samples which are taken from random people who are avaliable at the time of the sample. (People who always be trynna stop your boy in the streets smh)
- 14What are the advantage and disadvantages of Opportunity sampling?Adv: Easy to carry out
Inexpensive
Disadv: Unlikely to provide a representative sample
Very dependent on the researcher - 15Examples of: Qualitive/Catagorical Quantitative ---> Continuous or Discrete-Non numerical values like colours, food ETC
-Quantative are anything with numerical values. Can be Continuous (Does not need to be a whole number)
or
Discrete (Has to be an whole number) - 16(Class grouped data) What is the lower boundary? What is the higher boundary? How do you work out the midpoint? What is a class interval? How do you find out the class width?-The lowest number in grouped data
-The highest number in the grouped data
-The class width divided by 2 then add it to the lower class boundary
-A class interval is the smallest to largest intervals found in grouped data
-Higher boundary - Lower boundary = CW - 17—
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- A level Maths (Stats) Karteikarten am Statistics 1 : Data collection, erstellt von BUKDABOSS . am 28/02/2018.
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