This GCSE Geography quiz looks at sampling methods. Sampling is an essential technique in any geographical investigation, whether it is at school, in higher education or being carried out by a professional geographer. It is a short-cut method for investigating a large population. It is not usually practical to measure every single item within the parent population or area, so by sampling, it is possible to get statistically valid data that represents the whole. A key fact to remember about sampling is that it is never one hundred percent accurate, but if carried out well, it will give a very good estimate of what has been studied.
Sampling can be either random or systematic. If you have a study area that appears to be similar throughout e.g. a grassy meadow or a housing estate, you would choose to use random sampling as you are assuming that the conditions do not change from one part of the area to the next.
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When choosing where to sample, it should be done by generating two random numbers to use as co-ordinates. If you choose the random areas, it could introduce some bias to the results. In a natural environment, you could measure distances from a set starting point in the corner of the sample area or, when working in an urban environment, the random number pairs could be OS grid references. You can use the co-ordinates in different ways - point sampling, line sampling or area sampling. For point sampling, you would make your observations at the location described by the co-ordinates. For line sampling, you would generate a second set of co-ordinates and sample along a line joining the two points. For area sampling, you would use the co-ordinates to position your quadrat.
Where there is a difference across a sample area (termed an environmental gradient), systematic sampling is the method used. An example of this would be a school hockey pitch. Usually, the area around the goalmouth is trampled and mainly bare of plants. The most common methods are to use a line transect or a belt transect and sample either continuously or at regular intervals (interrupted transect). In the case of the hockey pitch, using continuous or interrupted belt transects that include the goalmouth areas or stratified systematic sampling (see next paragraph) would be appropriate. Other forms of systematic sampling would be every 10th house or every 5th person in the street. It could also be time based e.g. every 15 minutes during the day
Where there are significantly different parts to the study area (known as subsets), it is important to make sure that the samples you take are representative of each part. This is known as stratified sampling and can be either systematic or random. Examples of subsets in population studies would be age group or social group. An example of a subset in an environmental study would be a clearing in a woodland. The number of samples taken from each subset needs to be proportional to the whole survey.
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1.
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What is sampling? |
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[ ] |
Gathering data from books |
[ ] |
Counting every plant of different species in a field |
[ ] |
Generating random pairs of co-ordinates |
[ ] |
A short-cut method of investigating a large population or area |
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2.
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Sampling is: |
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[ ] |
a one hundred percent accurate measure of the population or area under study |
[ ] |
a good estimate of what has been studied |
[ ] |
visiting food shops and trying out some of the different foods on offer |
[ ] |
an unimportant part of fieldwork |
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3.
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Which of the following is a correct statement about random sampling? |
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[ ] |
The method used where the study area is the same throughout |
[ ] |
The method used where the study area is not the same throughout |
[ ] |
The investigator chooses where the samples will be taken |
[ ] |
They are all correct |
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4.
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Systematic sampling is: |
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[ ] |
an investigation into the systems used in a particular area |
[ ] |
only suited to places that are the same everywhere |
[ ] |
suitable for use where there is an environmental gradient |
[ ] |
not suitable for urban surveys |
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5.
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A quadrat could be used for environmental sampling in which of the following situations? |
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[ ] |
Interrupted belt transect of sand dunes |
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Continuous belt transect of the land from a farmers field to the edge of a lake |
[ ] |
Random sampling of a school playing field |
[ ] |
All of the above |
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6.
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When using a quadrat for random sampling, the co-ordinates give the position of which corner of the quadrat? |
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[ ] |
North west |
[ ] |
North east |
[ ] |
South east |
[ ] |
South west |
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7.
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What is objective data? |
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Information about the objects found in a survey |
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Data that does not rely on a personal opinion |
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Data that is obtained from a survey where people are protesting about something |
[ ] |
Data that is incorrect |
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8.
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Subjective data depends on which of the following? |
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[ ] |
Personal opinion |
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Clothing |
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Time of day |
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All of the above |
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9.
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Which of the following would require stratified sampling? |
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[ ] |
An investigation into a woodland which had a clearing in it |
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An investigation of the whole of the school grounds excluding the buildings |
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An investigation in which questions are answered by working people, elderly ladies and children at primary school |
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All of the above |
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10.
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Which of the following sampling methods would be the least practical for sampling the beetles living in a public park. |
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[ ] |
Random sampling with a quadrat |
[ ] |
Systematic sampling with a quadrat |
[ ] |
Continuous line transect |
[ ] |
None of the above are practical |
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1.
|
What is sampling? |
|
[ ] |
Gathering data from books |
[ ] |
Counting every plant of different species in a field |
[ ] |
Generating random pairs of co-ordinates |
[x] |
A short-cut method of investigating a large population or area |
|
|
2.
|
Sampling is: |
|
[ ] |
a one hundred percent accurate measure of the population or area under study |
[x] |
a good estimate of what has been studied |
[ ] |
visiting food shops and trying out some of the different foods on offer |
[ ] |
an unimportant part of fieldwork |
|
|
3.
|
Which of the following is a correct statement about random sampling? |
|
[x] |
The method used where the study area is the same throughout |
[ ] |
The method used where the study area is not the same throughout |
[ ] |
The investigator chooses where the samples will be taken |
[ ] |
They are all correct |
|
|
4.
|
Systematic sampling is: |
|
[ ] |
an investigation into the systems used in a particular area |
[ ] |
only suited to places that are the same everywhere |
[x] |
suitable for use where there is an environmental gradient |
[ ] |
not suitable for urban surveys |
|
|
5.
|
A quadrat could be used for environmental sampling in which of the following situations? |
|
[ ] |
Interrupted belt transect of sand dunes |
[ ] |
Continuous belt transect of the land from a farmers field to the edge of a lake |
[ ] |
Random sampling of a school playing field |
[x] |
All of the above |
|
|
6.
|
When using a quadrat for random sampling, the co-ordinates give the position of which corner of the quadrat? |
|
[ ] |
North west |
[ ] |
North east |
[ ] |
South east |
[x] |
South west |
|
|
7.
|
What is objective data? |
|
[ ] |
Information about the objects found in a survey |
[x] |
Data that does not rely on a personal opinion |
[ ] |
Data that is obtained from a survey where people are protesting about something |
[ ] |
Data that is incorrect |
|
|
8.
|
Subjective data depends on which of the following? |
|
[x] |
Personal opinion |
[ ] |
Clothing |
[ ] |
Time of day |
[ ] |
All of the above |
|
|
9.
|
Which of the following would require stratified sampling? |
|
[ ] |
An investigation into a woodland which had a clearing in it |
[ ] |
An investigation of the whole of the school grounds excluding the buildings |
[ ] |
An investigation in which questions are answered by working people, elderly ladies and children at primary school |
[x] |
All of the above |
|
|
10.
|
Which of the following sampling methods would be the least practical for sampling the beetles living in a public park. |
|
[ ] |
Random sampling with a quadrat |
[ ] |
Systematic sampling with a quadrat |
[x] |
Continuous line transect |
[ ] |
None of the above are practical |
|
|