Q2. How do we convert between measurements made by different instruments?

Further to George’s comment (http://wp.me/p7ffKH-B). This is one of the central questions I would like this working group to resolve. It starts with the simple question: What is #esd? Different people have different ideas about how to extrapolate their data into a 3D object. For example, I calculated ESD for each particle assuming faecal pellets are cylindrical and all other particles are prolate ellipsoids. But is that what everyone does? And how do you cope with aggregates that are made of different things stuck together? For example:

mixed aggregate

Further to that, how do you determine where a particle ends? I suspect most of us use automatic algorithms, but again, it would be important to make sure that we all use the same threshold. When dealing with 3D objects, even a small error in estimated ESD will have a large effect on final volume (e.g. POC content) calculations!

Maybe we can come up with definitions for each device, all of which are internally consistent?