Magic for Learning and Revision

Join Us
Sampling Methods
What would you use to sample beetles?

Sampling Methods

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.

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.

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
All of the above
The word stratified comes from the latin 'stratus' meaning 'layer'
Systematic sampling is:
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
Systematic in this sense indicates that samples will be taken at regular intervals
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
South west
In other words, the bottom left corner as you look at the quadrat
Sampling is:
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
It is the most important part of fieldwork since it provides the data for your analysis and conclusion
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
Continuous line transect
None of the above are practical
It would take a long time to complete (unless it was a very small public park!) and you would be very lucky indeed if a beetle crossed your transect line exactly at the moment you were looking at that point because they move around. Line transects are fine for vegetation surveys
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
All of the above
Quadrats are used in many environmental surveys
What is sampling?
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
Without sampling, studying a population or environment would usually take too much time
What is objective data?
Information about the objects found in a survey
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
It is data that can be measured using an instrument e.g. tape measure, quadrat or by counting
Subjective data depends on which of the following?
Personal opinion
Time of day
All of the above
An example of subjective data would be whether someone liked or disliked the design of a new bridge that had been built in the area of the survey
Which of the following is a correct statement about random sampling?
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
Random sampling is most appropriate for unifom areas and the sample locations should NEVER be chosen by the person doing the survey
Author:  Kev Woodward

© Copyright 2016-2024 - Education Quizzes
Work Innovate Ltd - Design | Development | Marketing

Valid HTML5

We use cookies to make your experience of our website better.

To comply with the new e-Privacy directive, we need to ask for your consent - I agree - No thanks - Find out more