SAMPLING TECHNIQUES Flashcards
The route to geographical enquiry has 7 steps. Can you list them.
The 6 steps are 1) identify an issue or hypothesis, 2) decide on what data is to be collected and how it should be collected, 3) collect and record the data, 4) present the data, 5) analyse and interpret the data, 6) conclude the enquiry, 7) evaluate the enquiry.
The first step of an investigation is to decided on a hypothesis. Describe what is meant by a hypothesis.
A hypothesis is a statement that can be proved or disproved.
List the 3 types of sampling techniques that could be used in a geographical enquiry.
The three types of sampling are 1) random, 2) systematic and 3) stratified.
What is meant by random sampling?
This is where you randomly decide which pebble to measure across the width of a river channel or randomly decide which person to interview.
Describe how you would randomly decide which person to interview.
A list of random numbers is needed to work out which people are going to be sampled. There are applications on the Internet that will generate a list of random numbers but many calculators also have a random number key. Use the generated list of random numbers to decide on which people to interview.
What is meant by systematic sampling?
Systematic sampling uses regular intervals to decide which people to interview or which pebbles to sample. In human geography you could interview every 5th members of the public that walked past you. In physical geography you could record the temperature at your school every 2nd day of the week.
When is stratified sampling used.
Stratified sampling is used when you know that a population has different subsets. For example, if a year 7 class contains 25% boys and 75% girls. Therefore, if you wanted to measure the height of the students you would take the height of 25 boys and 75 girls.
Suggest 2 reasons why you would carry out a sample of a very large ‘population’ set.
A large ‘population’ set would be sampled because it would be impossible to interview all of that ‘population’ set or it would take to long to interview all the ‘population’ set in the time you have been given to collect the data.
Describe the sampling technique that would be used when deciding where to locate 3 sites along the upper course of a river at which river velocity would be measured.
The sampling technique would be systematic. For example, each site could be 2 kilometres apart.
A group of students has set out to investigate if varies groups of people have differing opinions about the construction of a new shopping centre. The groups you want to interview are a) retired people, b) people who work and c) school children. Describe the sampling technique that would be used to decide who to interview.
The sampling technique that would be used is stratified.
What is meant by a ‘population set’?
A ‘population’ set is the total number of measurements that could possible be taken. For example if you interviewed every person that entered the High Cross Shopping Centre on a Saturday or if you measured the length of every pebble across the width of a river channel.
Describe 3 advantages of systematic sampling.
The 3 advantages of systematic sampling are that it is quick and easy to complete and it should stop you collecting biased data. For example, it should stop you only interviewing people who might appear to be cooperative or of a certain age group.
Describe 2 disadvantages of systematic sampling.
The 2 Disadvantages of systematic sampling are that it could easily miss sudden variations or small changes in the data. For example, if you were investigating a sand dune transect and your sample sites are 20 meters apart you could easily miss some changes in vegetation type, such as a small dune slack.
