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Sampling and Correlational Studies (Different types of sampling (Random…
Sampling and Correlational Studies
Different types of sampling
Random Sampling
Opportunity Sampling
Systematic Sampling
Stratified Sampling
Quota Sampling
Self-selected Sampling
Snowball Sampling
Snowball Sampling
Find one person you want to study and get that person to ask their friends to take part in the study alongside them.
Stratified and Quota Sampling
Choose your target population and then use the sampling frame to decide who to use from the target population. For stratified you should use a random generator and for Quota you could knock on people's doors and ask them to join your study.
Systematic Sampling
This requires the researcher to use equipment such as a phone book to choose their participants. For example the researcher finds every 5th person in the book and uses them in the study.
Random Sampling
The researcher puts everyone's name into a random generator and then randomly picks out the participants.
Opportunity Sampling
The researcher uses the first people that come along at the time in their study. Completely by chance of whoever comes along.
Self-selected Sampling
The researcher just chooses anyone they want to be in their study from wherever they choose.
Types of correlation
Positive
As one co-variable goes up, so does the other.
Negative
As one co-variable increases the other decreases
Zero
There is no pattern between the 2 co-variable at all.
Scattergraphs
Scattergraphs shown the relationship between two co-variables and this is the only graph that can be used to plot a correlation.
You can test the strength of a correlation using a co-efficient. This is a number between -1 and +1 and the close the number is to zero, the weaker the correlation is.
Hypothesis
Directional
There will be a significant positive correlation between the number of marks (1-50) given by the teacher and the number of marks (1-50) given by the exam board.
Non-directional
There will be a significant correlation between the number of marks (1-50) given by the teacher and the number of marks (1-50) given by the exam board.
Null
There will be no significant different between the number of marks (1-50) given by the teacher and the number of marks (1-50) given by the exam board.
Advantages
They can lead to experimental research which can be carried out
They can be very reliable and can be repeated really easily which means it's easy to see how accurate the results are.
Disadvantages
Can not be used to establish cause and effect because there could be extraneous variable that are affecting the research.
People can misinterpret them like the media which could lead to false conclusions.
What is a correlational study?
A correlational study is a non-experimental study used to find the relationship between two co-variables. There is no IV and DV.