Running a pilot study

To work out how pea crabs affect mussel growth, Oliver Trottier (Leigh Marine Laboratory) collected thousands of green-lipped mussels from a single farm off Great Barrier Island, but first, he and his colleagues carried out a pilot study. This small-scale version of the larger experiment gave Oliver an indication of what results he could expect. In this video clip, Oliver describes how and why he did his pilot study, and how the results led him to change his experimental approach.

Focus questions:
What is a pilot study?
Why did Oliver choose to do a pilot study before his main experiment?
How did the results from the pilot study affect how Oliver carried out his main experiment?

Transcript

Oliver Trottier (Leigh Marine Laboratory)
We did a very brief pilot study, almost the same approach as I was going to do for the main study on a much, much, much smaller scale.

There was only about 20 points at three different depths that we sampled, brought those in really quick, had everybody on board, go through all the mussels, shuck them and give me numbers of the pea crabs they were getting at each individual depth and where they were on the farm.

For each sample bag that I was bringing in, I was getting a one or a zero, or a zero, or a zero, or a one because I wasn’t putting enough mussels in the bag. And that sort of data really doesn’t tell you anything about abundance and where the crabs are in the farm, and that was some of the questions that I wanted to answer. So when I started to get those results in the pilot, I changed the set-up and put more mussels into each bag but sampled from less places, so it gave me a better picture on the whole about the infection level and what’s happening on the farm.

The pilot study was to ensure that the data that we were going to collect was going to be usable, because to put such an effort and so much energy and finances and work behind it and bring back a whole bunch of mussels, it was going to give me data that I couldn’t use or wouldn’t tell me about what’s actually happening on the farm. It just would’ve been a bit of a waste of time.