Just what is sampling?
As psychologists we use different sampling methods to find trends within a population. Testing the whole population can be both expensive and time consuming, so for this reason it is much easier to test a representative sample of the population. From the results of testing this sample we can make an assumption across the rest of the population and progress our research from there.
So what can go wrong?
Well for a start we have to look at ‘sampling biases. If the participants were not selected randomly, they may have been chosen with the aim of generating the best results relevant to the test – this can seriously undermine the validity of the test. For this reason it could be said we should aim to use a ‘random sampling method’
While more reliable in one respect, it generates the issue. As the participants are chosen at random, the minority of the population could be chosen entirely and outweigh the majority in the sample. For example, if we were to look at the amount of people with a learning difficulty in a small town of 100 people, we could end up with a sample of 30 with a learning difficulty and 20 without – Whereas true results should show 30 with learning difficulties and 70 without. This problem can be helped by selecting a much larger sample, but it will still exist, albeit to a lesser extent.
But what about individual differences?
Everyone is different. This is something we should be taking into account as Psychologists – After all, it’s what our work as all about. But does this mean that the results from a tested sample cannot apply to the rest of our population? Well, in my view yes and no. We can say that there is a ‘good chance’ our results will also apply across the rest of the population, but we cannot confirm this to 100%.
Okay, but that’s just a sample. What if we tested the whole population?
While testing a whole population would be both time consuming and expensive, we could gain some much more accurate information from the results. However, the problem would exist again in that we could not necessarily apply these results across any more than the population tested. Simply put, to apply results to the rest of the world, or even one country, we would have to take into account individual differences and cultural biases on a much larger scale.
So is there any point?
Yes. Even though all of the above seems to run the idea of sampling a population into the ground, the act of sampling does give us a very good idea of how to progress our research. Sampling helps us to understand trends in a population and points us in the right direction for further research; without it we would be pretty much ‘stabbing in the dark’ to find a conclusion.