Statistics Definitions Flashcards
Define population
The whole set of items that are of interest to
Define a sample
Some subset of the population intended to represent the population.
What is a sampling unit
Each individual within the pop. That can be sampled
What is a sampling frame
A list of all the units in the pop.
Define a statistic
A value calculated from a sample data e.g mean
Define a parameter
A value calc. From the pop. Data
Define a census
Data collected from the entire pop.
State the adv and disadvantages of a census
Advantages-
high accuracy
Dis-
time consuming
Expensive
Large vol. of data to process
Sate the disadvantage and advantages of a sample
Advantages-
Cheaper
Quicker
Less data to process
Disadvantages-
Not as accurate
Data may not be large enough to represent small sub-groups
Explain simple random sampling
This is when each item in the sampling frame has an identifying number. And a random number generator is used to pick the items randomly
Define random
Every item in the sampling frame has an equal chance of being chosen
State the advantages and disadvantages of simple random sampling
Adv -
Bias free
Easy+cheap
Each number has a known chance of being selected
Disadvantage-
Not suitable when pop. Is large
Sampling frame needed
Explain systematic sampling
Required elements are hoses at regular intervals in ordered list,
To take the k^th elements where:
K= pop size/samp size
Then choosing a random number between 1 and k
State the adv and disadv of systematic sampling
Adv-
Simple and quick
Suitable for large pop
Disadv-
Sampling frame needed
Can introduce bias if the sampling frame is not random
Explain stratified sampling
Pop is divided into groups and a simple random sample is carried out in each group.
