What should and shouldn’t be in an experimental record

Your experimental record should be completed while an activity is conducted to record observations pertinent to the activity, such as procedures, equipment, results and observations, as they occur. A common error when keeping an experimental record is to note down the measurements from the experiment and worry about other information, such as the methods used to capture that data, some time later, maybe when you have more time and are not focused on the task of actually performing the experiment. The problem with doing this is that key information needs to be recalled from memory, which means it could be miss remembered or forgotten.

Lab books are working documents created while practical activities are occurring, so they do not need to be immaculately presented. It is vital they are legible and ordered, so they can be referred to later and understood, but do not need to be of presentation or publication standard. If you make a mistake with what you have written, do not try to completely cover it by scribbling out. Simply cross it out with a single line though the work to show that it was written in error, but the original content can still be read. Place the correct information elsewhere on the page.

There is a good reason why lab books are used over, say, photographs and videos for recording what happens in a laboratory. Using a written lab book allows you to quickly create tables, sketches, text, numbers, annotation...etc all in one place. Writing a lab book allows you the discretion to record only the information you believe is important. For example, if you need to record the reading from a gauge, you could take a photograph showing the value. However, if there are a series of readings you need to take, this will mean opening numerous photographs to obtain the data and the photograph won’t capture any uncertainty associated with, for example, parallax or variation with time.

The correct level of detail

The amount of information to keep in an experimental record is a delicate balance and requires a skill that is developed with experience. Too much detail means you spend far too much time collecting and writing down information, and it is more challenging to pick though after the experiment if you need to track down something specific. Too little and you may miss recording critical information that is required after the experiment has been completed. The correct amount of information to record about what you did should be just enough for you or a colleague to recreate or repeat the experiment should this be required. The amount of measurements and observations should be enough to analyse and interpret the results. The level of detail should be sufficient to write a full laboratory report to document the experiment without having to return to the laboratory to get additional information. Your lab book should allow you to write a report weeks, months, or years after the experiment was conducted: long after you have forgotten the details.

Making the decision about what may or may not be pertinent information to write down can be tricky, especially when you are developing your skills in keeping an experimental record. If in doubt, it is better to record information rather than leave it out, even if it later turns out to be superfluous. It is usually much cheaper to use an extra bit of paper to write down some unnecessary details than to recreate an entire experiment, if indeed it is even possible to replicate the exact, original conditions.

Structuring an experimental record

You may need to refer back to your lab book long after you have forgotten about the experiment, or may need to pass it onto someone else to read to find out what has been done. So it’s important to make the layout of your experimental record clear and logical. This is typically done by separating the content into sections that make sense for the particular experiment. As experiments can vary significantly in their aim, discipline and context, there are no specific rules about what sections should and shouldn’t be included. However, there are some typical sections that you might find in most lab books, listed in the next section. It is, however, critical that there is a clear delineation in any experimental record between the data you have recorded during the experiment, and any processing, analysis or interpretation of that data. What actually happened in an experiment is a matter of fact and your interpretation of the data is a matter of opinion. It is entirely reasonable for someone else to question your interpretation of results or suggest you have made an error in how some data has been processed, but this cannot be done with the record of what was done and the data obtained.

Recording the date, time and location

There are some items you would expect to see on all experimental records. The first is the data and time that the experiment was conducted. This is critical information to record for two reasons.

1. The conditions at that time could have influenced the results of a test. For example, if a test for a certain material is conducted on a particularly hot or humid day, this could have had a significant influence on the results.
2. When a discovery has been made, the date and time can determine who gets credit. As experiments are designed to establish knowledge that was not previously known, an experimental record can be used as evidence for who made a new discovery first.

When writing the date and time it is important to ensure the format chosen can’t be misinterpreted. For example, the american date format typically puts the number of the month before the number of the day. The data 6/12/19 would be considered the 6th of December 2019 to a British Reader and the 12th June 2019 to an American reader. It is therefore wise to write the month using words rather than numbers to avoid misinterpretation. A similar confusion can be caused by the 12 and 24 hour time formats. So it is wise to always include the AM or PM or specify 24 hour time is being used.

For the same reasons you record date and time, it is also important to record the location of the laboratory in which the experiment was conducted, for example the “Materials Laboratory (2.03), the Diamond Building, University of Sheffield”. Finally, there will be some administrative details that should be recorded for each activity you conduct, especially if performing the test as part of the work you do for an organisation. In a University, this might be a module title or number with which the experiment is associated or for an employer it may be a team name or customer account number.