Sampling methods

Question 1

what are the conditions for an accurate sample?

Answer 1

• Unbias

- Representative of the population

Question 2

What will samples always have?

Answer 2

-Sampling error or variation due to sampling

→Because we are looking at a part of the population not whole

Question 3

Random sampling

Answer 3

-List the members and choose random numbers to decide which members are in the sample

Question 4

☺Advantages of random sampling

Answer 4

• Can be used with large sample of population
• Avoid bias
• Representative result

Question 5

☹Disadvantages of random sampling

Answer 5

-Can lead to poor representation of overall population or area of large areas are not hit by random numbers generated

Question 6

Systematic sampling

Answer 6

-Starting from random in the population or points and then systematically take numbers at a certain number apart. (e.g. every 20 people, 10 meters or every 5 minutes to be sampled)

Question 7

☺Advantages of systematic sampling

Answer 7

• A good coverage of the studied area

- Can be more easily achieved and more straight forward than random sampling

Question 8

☹Disadvantages of systematic sampling

Answer 8

-More bias as not all members or points have an equal chance of being sampled

Question 9

Stratified sampling

Answer 9

• Stratas (groups) are chosen specifically to represent different characteristics within the population
• And then within each group a random sample is taken

Question 10

☺Advantages of stratified sampling

Answer 10

• Unbias and representative sample

- comparisons can be made between stratas

Question 11

☹Disadvantages of stratified sampling

Answer 11

• If stratas are inaccurate results will be unreliable

- Depending on the time of day certain people might not be present