An important part of my work involes identifying pieces of evidence that are crucial for a particular decision (crucial considerations or cruxes), then figuring out how to get that evidence.

Of course, a rigorous data set or publication (or even a systematic review!) is ideal. But this high-quality evidence doesn’t always exist.

In these cases, it may be necessary to rely on expert opinion. Expert opinion is more likely to be a good source of evidence when you’re looking for factual (empirical) information and when the expert(s) in question are well-informed and well-calibrated with regards to this piece of information.

If you can write down the piece of evidence that you need specifically, then it’s basically just a creative challenge to think of who can tell you that piece of information.

Examples:

  • Academics will often respond to a short and polite email and have email address listed on their website or publications, e.g. agricultural economists working on broiler production in some country, or dermatologists who might know something about the biology of particular mites!
  • Professionals in fields with skill sets relating to a question, e.g. a nurse might be able to quickly tell you some details about a particular hypothetical hospital scenario.
  • Governments often have records relating to various social and industrial metrics. These are frequently in obvious places, e.g. agriculture census data to estimate the number of animals farmed in a country, but sometimes are non-obvious, e.g. water quality monitoring programmes for human health reasons can tell you something about the water quality in floating-cage aquaculture. This information is frequently public, but when the information is non-public, the government will often release the data if you ask and/or submit a freedom-of-information request (we did this in Denmark and got excellent evidence on whether or not Danish fish farms were using their maximum nitrogen emission quotas).
  • People who live locally can easily gather information that is publicly visible in a certain location but not published, e.g. my colleague Koen happens to live in a town in the Netherlands that is an important shrimp landing port and so could tell me some information about the size and number of fishing vessels.
  • Some particular forms of information show up in sensor or monitoring data. This can include satellite data (e.g. true-colour images or various metrics, like the vegetation index or the chlorophyll index); atmospheric and weather data (e.g. even simple temperature can tell you something about the external conditions during animal transport, and Max M and I used UV index data, published for skin cancer prevention, as a proxy for sunlight in a study about soil temperature); global sensor data products (e.g. we used a sea-surface height map to answer a specific question we had about aquaculture harvest vessels in the Mediterranean); and orthophotographs (for high-resolution true-colour images).
  • Historical archives can often provide a small number of highly important historical data points, either online (as I did for my recent blog post on the Porties reef) or in person (the best example being Heidi Alleway’s 2015 paper on the long-term changes in oyster distributions in South Australia)
  • Large companies are often happy to provide information on production methods (if you make sure to word the question well and interpret the response in the context of a for-profit company trying to sell a product). e.g. I recently messaged Coles and Woolworths on Facebook and got a detailed picture of the main slaughter methods in Australian shrimp aquaculture.
  • Lots of detailed discussion in online hobby communities (as I detailed in a recent blog post!), either as publicly posted information or as an avenue for asking specific questions. e.g. in Saulius Šimčikas’s post on rodent welfare (rodents are farmed for snake food), a snake hobbyist provided Saulius with very useful information that helepd Saulius to estimate the numbers of rodents (see the comments section).
  • Many people on Fiverr hire out specific skills for very affordable prices. This is particularly useful for high-importance emails or communications in foreign languages (I don’t trust automatic translation for this purpose). I once had a whole conversation with an officer in Israel’s department of agriculture about the effects of a particular slaughterhouse policy this way.
  • Collecting the data yourself. I’m always surprised at the variety of things that can be purchased online for minimal cost and zero effort; one upside of the “cheap plastic crap” world that we live in! This includes everything from scientific equipment to take your own measurements (e.g. lux meters to measure light intensity, cheap microscope lenses to look at invertebrates in detail using your phone camera, even high-quality light microscopes are reasonably affordable) to supplies for specific occupations (e.g. pig teeth clippers from farm supply store, which I used as a prop in my talk at EAGx last year; or communion wine from Christian supply stores, dont ask!)