Sampling Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is sampling?

A

taking measurements of a limited number of individual organisms present in a particular area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is sampling used for?

A

used to estimate the number of organisms in an area without having to count them all

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the number of individuals present in an area known as?

A

the abundance of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How can sampling be used to measure a characteristic?

A

e.g. height

you cannot measure all plants, you can measure some and take an average

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is random sampling?

A

selecting individuals by chance

each individual has an equal chance of selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is random sampling done?

A

1) mark out a grid on the grass using two tape measures laid at right angles
2) use random numbers to determine the x coordinate and y
3) take a sample at each of the coordinate pairs generated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is opportunistic non-random sampling?

A

may not be representative of the population - weakest

uses organisms that are conveniently available

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is stratified non-random sampling?

A

populations can be divided into a number of strata based on characteristics

e.g. male and female

a random sample is then taken from each of these strata proportionate to its size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is systematic non-random sampling??

A

often uses a line or a belt transect

line transect - marking a line between poles, describes organisms which touch the line or distances of samples from the line - used to show how distribtuion changes

belt transect- two parallel lines are marked and samples are taken of the area between the two lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is there a sampling bias?

A

selection process may be biased

may choose to sample a area that has more flowers because it looks interesting

can be reduced using random sampling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are the results affected by chance? How can this be minimised

A

there is a chance there may be more or fewer plants in a area by chance, not representative of the whole population

minimised using large sample size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are often the limitations

A

biased - not representative

too few samples take - not valied

misidentification/msicount - not accurate

distribtuion and abundance changes over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly