9. LABORATORY RECORDS AND REPORTS
9.1 PREPARATION FOR THE LABORATORY
9.2 THE LABORATORY RECORD
Scientists and engineers record laboratory data in bound notebooks with pre-numbered pages. These books serve as a permanent record of the work, and can serve as legal evidence in priority disputes. Some instructors insist that students in science laboratories keep such notebooks. Whether required or not, the use of a notebook helps you to develop good laboratory habits that will serve you well in your future career.
Your laboratory notebook reflects your personal style, but you should write it so that a co-worker familiar with the subject of your research could understand it. Such a person may need to obtain information from your notebook. You may need to refer to the notebook at a later date, therefore do not omit any information necessary to understand what you did, or to repeat it.
Use a bound (not a loose leaf) notebook for the laboratory record. Make notebook entries as the experiment progresses, as a running record of the work. The notebook includes a complete history of all experiments performed, and their results.
Quadrille-ruled pages with 1/4 inch squares facilitate making data tables and rough graphs. Don't erase anything in a laboratory notebook, and never remove pages from it. Line out, and annotate, mistakes. Use permanent ink, for better readability. You may abbreviate, but make all entries clear, organized and complete"and neat enough for you, or someone else, to read.
Here's a check list of items which you should record in the notebook:
The reader won't expect the lab notebook to contain a condensed and polished report of the experiment, but will expect to find enough evidence to determine what you did, how you did it, and what results you obtained.
9.3 THE LABORATORY REPORT
The laboratory notebook provides a personal record documenting the progress of the experiment. The laboratory report serves a quite different purpose. It communicates your experimental work to other persons. This demands a different style and approach.
All "real" scientific work of any value (and some that isn't) eventually finds expression in a written report. In industrial research and development, reports communicate to supervisors and directors, may circulate internally within the company, and may even reach other scientists in the same field around the world. Some reports get published in technical and scientific journals. Even technicians sometimes write reports.
Many a scientist or engineer discovers the hard way that people judge the quality of experimental work by the quality of the reports. Ineffective reports may cause people to ignore the research itself, and, on a very practical level, may jeopardize the funding of that research.
Style and appearance of reports:
Essential parts of the report:
Here's a list of the usual parts of a complete report. The nature of the experiment will determine which ones are necessary, and the appropriate heading for each.
Avoid unnecessary duplication. Don't include data and procedure in the results section. Don't include minor details of procedure, theory and results in the abstract. Include only material directly related to what you did in the experiment. Omit idle speculation.
9.4 FORMAL AND INFORMAL REPORTS
The informal report differs from the formal report in three major respects. The informal report omits: (1) the abstract, (2) description of procedure (except where there were significant deviations from the procedures of the instruction manual), and (3) exposition of the physics underlying the experiment.
Your instructor may want a copy of your laboratory record included as an appendix to the report, for completeness. This will include the equipment list, original data, calculations, preliminary graphs and sketches, record of observations made in the laboratory, etc. The instructor may, in the informal report, allow you to insert this after the "purpose" section of the report, to preserve chronological continuity. Don't expect that anyone will necessarily read this! Whatever you want the reader, or instructor, to consider in evaluating your work must appear in its appropriate place elsewhere in the report.
9.5 GENERAL CONSIDERATIONS OF REPORT WRITING
A real experiment may occupy months or years. The laboratory record may consist of several filled notebooks, computer printouts, photographs, charts, etc. You must distill, reorganize and repackage this scattered source material into a clear and concise document of a just a few pages. The report must communicate efficiently. It must have a clear and logical structure which allows the reader to extract the essential points easily.
Readers of your report want to know what you accomplished, and you must say that clearly and effectively. Every experiment has certain objectives, and you must state the extent to which these were accomplished. If you set out to determine the constancy of the acceleration due to gravity, you must, in your discussion of results, state whether your experiment demonstrated its constancy, and within what uncertainty. If you set out to measure the size of the acceleration due to gravity, you must give your one best determination of that acceleration, along with its estimated uncertainty. These statements must appear in the "results" section, even if they appear elsewhere in the report.
9.8 DISCUSSION AND ANALYSIS OF ERRORS (UNCERTAINTIES)
9.9 DISCUSSION OF RESULTS, AND CONCLUSIONS
Students benefit from study groups, learning from each other. Strongly resist the temptation to rely too heavily on others. When exam time comes, you must work alone.
Laboratory partners discuss each experiment and share ideas. But in a classroom situation the written report represents your own work, not that of a committee. Don't let others do your thinking and analysis.
Partners' data will, of course, consist of the same sets of numbers, but each partner will organize the report to suit his or her own personal tastes and style. Each will do the data analysis independently. Partner's reports will, therefore, not look alike, even superficially. When partners make identical mistakes, this raises suspicions that one must have copied without thinking. Plagiarizing something wrong or absurd makes one appear not merely unprofessional, but also thoughtlessly lazy! Signing your name to a totally wrong statement copied word-for-word from someone else demonstrates your inability or unwillingness to think the matter through on your own. Better to make your own mistakes, honestly. Better yet, use critical thinking to discover your mistakes, and those of others.
When you write the discussion of results yourself you'll gain the valuable experience of drawing your own conclusions, unprejudiced by the opinions of anyone else. All details of the report will reflect your individual style and individuality.
9.11 THINGS YOU SHOULDN'T DO
Don't include idle speculation about sources of error. To say that certain conditions of the experiment "may have caused error" communicates no useful information unless you cite some specific evidence or a plausible mechanism pointing to that fact.
Don't include such trivial comments as: "The resuslts may have "human error." We all know that human blunders, misperceptions, and misinterpretations can occur. We expect the experimenter to take every precaution to avoid them. This "goes without saying." The other classes of "human error" due to limitations of instruments, and limits of human observation of instruments belong in the quantitative error discussion.
Likewise, don't say "Error in results could arise from calculation errors." If you mean blunders, this statement tells us nothing we didn't already know (we still wouldn't know whether there were blunders). If you mean the error introduced by calculating devices, then you haven't done your job properly. Your responsibility includes choosing calculation techniques that do not introduce significant error. You should do everything necessary to keep calculation errors negligible compared to the experimental errors. If for any reason you did not, or could not, accomplish this, you must give good reason why you didn't.
Most elements of good style common to other types of writing also apply to scientific writing. One of the best general references for the student is:
Strunk, William, Jr., and White, E. B. The Elements of Style. Macmillan Paperbacks, 1962.This book demonstrates by example the clarity and brevity that it advocates. The 1918 edition may be found online and has internal links, which are very handy.
Other useful references are:
On matters of technical style for research journals, consult The American Institute of Physics Style Manual.
Examples of style faults.
We list below some faults frequently found on student laboratory reports, with suggestions for improvement.
(2) "The acceleration of gravity, one of the most fundamental constants in physics..."
(3) "In this experiment we proved the truth of the law F = ma and measured the value of the acceleration."
(4) "We located the apparatus in the northeast corner of room 216 of the science building, in a sunny spot on a maple table 31 inches from the floor."
(5) "I enjoyed this experiment very much and learned a lot from it."
(6) "Due to poor equipment we didn't get good results."
(7) Our results agreed exactly with the textbook value, so we consider the experiment a success."
(8) "A force of 9 kg stretched the spring 5 cm, therefore it did work (9)(0.05)(9.8)/2 = 22.05 Nt. From this we calculated the efficiency of the spring by..."
9.13 LABORATORY ETIQUETTE
You and your partner will have an assigned work area or work station, which no one else shall disturb. Your responsibility includes keeping it in proper order. You will use equipment and parts stored in trays or drawers in an orderly fashion. Keep it in that order, for your own convenience, and out of consideration for other students who will follow you.
Keep your work area uncluttered. Store all instruments and components not actively in use in their proper place, away from your work area, or in the special storage cabinets.
You may need other equipment and components stored in a different area from your work station, perhaps in drawers or bins, or on shelves in the stockroom. Return these to their proper place immediately when you have finished with them.
Don't make unauthorized modifications to the equipment.
Don't use any kind of tape, markers, or ink on laboratory equipment.
Report damaged equipment or components to the laboratory instructor, for prompt repair or replacement.
[An E-prime document.]
Document © 1996, 2010 By Dr. Donald E. Simanek, Lock Haven University of Pennsylvania. It may not be sold or used commercially for profit without permission of the author. Teachers may freely use this document and distribute it to students without charge provided it includes this copyright notice.
The author welcomes suggestions for additions and improvement. Send to: this address: