11.2 Types Of Sampling

Question 1

Sampling

Answer 1

Taking measurements of a limited number of individual organisms present in a particular area. Two types: random and non-random

Question 2

Random sampling

Answer 2

Selecting individuals by chance. Random number generators must be used to there is no bias in the choosing.

Question 3

Non-random sampling

Answer 3

3 types: opportunistic, stratified and systematic.

Question 4

Opportunistic sampling

Answer 4

Uses organisms that are conveniently available

Question 5

Stratified sampling

Answer 5

Some populations can be divided into strata (sub-groups). Random sample is taken from each strata proportional to relative size

Question 6

Systematic sampling

Answer 6

Often involves belt or line transect. Samples areas at identical intervals

Question 7

Sampling bias

Answer 7

Selection may be biased by accident or deliberately. Eg. Choosing a patch of flowers because it looks interesting.

Question 8

Chance (reliability)

Answer 8

Organisms selected may, by chance, not be representative of the entire population. Eg. The 5 worms selected caught first may be the longest 5 in the habitat. Greater the sample size, the lower the likelihood of this occuring