Whenever I am preparing to give a talk in a public forum, I will ask people what information they think I should present about my topic. The majority of people will say "present all of the information!"
All of the information? The problem is that all of the information is not really useful, and can even be counter-productive.
For example, if I am describing the results of my research to an audience, I discuss only the data that I am actually using to draw my conclusions, as well as information that I think may be problematic and need to address. Is it possible that there is other data that I am not aware of or that I think is irrelevant that would change my results if I accounted for it properly? Yes, it is. In fact, I have had the experience of dismantling the results of other researchers simply by taking into account information that they thought was irrelevant, and future researchers may have the same experience with my work.
However, to present all of the information presents its own problems. First off, most of it is irrelevant to research. Secondly, the amount of information is so huge that to present it all would both overwhelm the audience (not to mention bore the hell out of them) and also produce a number of red herrings that could distract from important information. Let me provide a list of the information present in our field and lab notes, and this may help to illustrate my point:
- What is the nature of the project (survey, excavation, record search, lab work, etc.)?
- How many crew members were present? Who were the crew members? What are my general impressions of the individual crew members?
- If it is a survey that is being reported, then what was the spacing of the transects (how far apart did the crew stand while surveying), what was the soil visibility, lighting conditions (sunny, overcast, morning, noon, afternoon, etc.), local vegetation present, etc.?
- If it is an excavation, then how many units (square holes) and shovel probes (smaller holes) did we dig? How deep are they? What was in each unit? What type of mesh did we use to screen the soils.
- What is the soil like? Is it sandy? Silty? Clay? Loam? What color is it? Is it easy to walk across, or do you sink into it with each step?
- Did any of the crew sustain injuries while working on the project? What kind of injuries? How severe were they?
- Did we work on a ten day schedule (M through Th of the following week, with four days off between sessions), or a five-day schedule (average M-F work week)? Did we work 8 hour days? Ten hour days?
- Is our client paying for drive time to get us to and from the field, or do we east that time ourselves?
- Is everyone on the crew wearing appropriate clothing for the field, or are they doing something wrong (forget their hat, no sunscreen, not wearing boots, etc.)?
- Are we sorting material in the screen while in the field, or dumping everything into bags to be sorted back at the lab?
- At the lab, who's working? What's the lighting like? Is the radio playing? Is there talking amongst the lab technicians?
...and so on. Now, there's a fair chance that you are thinking to yourself "well, of course I don't want all of that information. I only want the relevant information!"
But how do we decided what's relevant?
The size of the screens used in excavation has bearing on what types of materials are likely to be recovered (a large screen size may lose beads and smaller animal bones, for example, but will allow you to excavate more soil and therefore get a larger sample of material from the site). If the soil color or texture is close enough to the color or texture of the artifacts being searched for, then they may be missed. Screen-sorting of artifacts in the field is efficient and allows more material to be dealt with quickly, but also results in materials being lost that would be recovered if the material is sorted in a lab. Some materials are most visible on a sunny day, others on a cloudy day.
Even things that seem clearly irrelevant may not be. A field technician who doesn't wear a hat may find their eyes strained when working in bright sunlight, causing them to miss artifacts that they would otherwise see. An archaeologist who is not dressed appropriately for the field may became distracted by physical discomfort and miss items that they would otherwise have found. The same goes for workers who are distracted by injuries, personal problems, etc. Workers who haven't eaten a proper breakfast may be having so much trouble simply keeping up that they will fail to do a decent job as archaeologists.
The point is that there are very few pieces of information that could not be argued to be in some-way relevant under the right conditions. And yet, I sincerely doubt that an audience who come to a talk to hear about the latest archaeological findings has much desire to hear about how many of my field crew had fights with their spouses, or whether they thought that fashion trumped practicality in choosing their field gear. And, in truth, most of the time the effects of these factors on field results are negligible. However, there are unusual cases where they have had a significant impact. On the other hand, thing such as screen size and soil conditions have a tremendous impact on results, but I have found that bringing these up with the public pretty much always results in them tuning you out.
Providing "all of the information" is not only impractical, but actually a bad idea. It doesn't usually inform the audience, may provide them with false leads, and they generally don't even want to hear it even if they had previously said otherwise. In the end, we have to rely on our professional judgement to determine what information is relevant. Most of the time we do get it right, but it is a good idea to keep in mind that we are having to do this whenever you hear an archaeologist talk.