Statistics - Sampling and Data Presentation

Question 1

What is simple random sampling?

Answer 1

Where every sample has an equal chance of being selected
Every item in population assigned number which is randomly selected

Question 2

Pros and Cons of simple random sampling?

Answer 2

Pros:
No bias
Easy and cheap to implement on small populations
Cons:
Less Suitable for large population
Sampling frame needed

Question 3

What is systematic sampling?

Answer 3

Samples taken at regular intervals from an ordered list

Question 4

Pros and Cons of systematic sampling?

Answer 4

Pros:
Easy and quick
Suitable for large populations
Cons:
Sampling frame needed
Bias if sampling frame is not random

Question 5

What is stratafied sampling?

Answer 5

Population is divided into mutually exclusive strata and a random sample is taken from each

Question 6

Pros and Cons of stratafied sampling?

Answer 6

Pros:
Sample accurately reflects population structure
Proportional representation
Cons:
Random within each strata
More time consuming

Question 7

What is quota sampling?

Answer 7

Population divided into groups based on a given characteristic
Interviwer interviews someone, then allocates them into a group until all groups are full

Question 8

Pros and Cons of quota sampling?

Answer 8

Pros:
Representative of population
Comparison between groups
Cons:
Dividing into groups can take longer
Non-random can introduce sampling

Question 9

What is opportunity sampling?

Answer 9

Taking samples from people whop are readily available at the time study is carried out and who fit criteria

Question 10

Pros and Cons of opportunity sampling?

Answer 10

Pros:
East and cheap
Cons:
Not likely to be representative of population, depends on location, etc.

Question 11

What makes something an outlier?

Answer 11

Data 1.5x IQR below/above lower/upper quartile
Or outside 2σ from mean