How to set up a population study
Create your own study by following these steps
Choose your population
In this section we’ll use the common periwinkle (Littorina littorea) and the seaweed (a type of algae) that provides its habitat, dabberlocks (Alaria esculenta), as examples, but most of the questions we’ll ask can apply to any population. Consider the extent of your survey. Do you want to sample the population of a single beach or an entire coastline? What is feasible in the time that you have?
What do you want to find out?
Are you just counting the numbers of periwinkles and dabberlocks algae? Perhaps you’re interested in something more complex like behaviour, disease or size/age? Do you want to compare populations at different sites or at different times? Devise a method that will allow you to collect the particular information you need.
What sort of samples will you collect?
How many samples will you need to take? How can you ensure all the samples are taken in the same way? Will you use random or systematic sampling? You may want to divide your survey area into zones or decide how many periwinkles to sample at each survey location. Write up your method, making it clear enough for someone else to follow it.
How will you identify members of your population?
Do you know what dabberlocks looks like? How will you tell it apart from other seaweeds? An identification chart is useful. (See this seaweed example. Can you create something similar for periwinkles?)
What will you need to take with you?
Remember your identification chart and anything you’ll need to take your samples or record the data you are collecting. Are there any other practical items that you might need, like wellies or warm clothes? Have you completed a risk assessment?
What will you do with your data?
When you’ve collected your data, how will you know what they mean? Will you have to calculate ranges or averages? How will you show if your results are significant? Think about the amount of data you will produce, whether you have enough time to analyse them, and how you could display your results visually, so that they are easy to understand.
How will you communicate your results?
Once you’ve analysed your data, you’ll be able to see if and why your results are important. Decide how you’re going to convey their importance to others, so they can build on the knowledge.Lead image:
Известный символ Украинской культуры/Flickr CC BY NC