This guide for the writing of laboratory reports is intended to help you write your reports and to understand the criticisms of them made by your instructors. You should study this guide before writing each report, review it before turning in each report, and use it to help interpret the criticism on reports returned to you.
You write reports in this course not only to explain the experiments performed and what you learned from them, but also to learn, under the guidance of you instructors, something about the kind of writing you will be expected to do as an engineer.
Engineers write many kinds of reports. Some of these, perhaps most, may be called routine reports, involving the filling in of blanks in a report sheet, or the supplying of tables, graphs, or drawings, with perhaps only a few sentences of explanation here and there. The routine report is read by those are closely familiar with the writer’s work. They know what to look for and want facts quickly; hence elaborate introductions, transitions, and explanations are usually unnecessary in this kind of report. We are not concerned with the preparation of the routine reports in this course.
The second kind of report written by engineers and usually the most difficult to prepare may be called the special report on a project. This is the kind of report we ask you to write in this course. The special report must be fully developed and completely self-sufficient. It must be intelligible to a number of readers, most of whom are not specialists in the subject of investigation, and who may know nothing about the writer and what was done except for what the report itself tells them. And it should be just as clear to a reader ten years later as it was on the day it was first submitted. Thus the special report must be COMPLETE – It must give all the facts necessary for an understanding of the problem, the method of investigation, the results obtained, and the significance of these results. And it must be QUIETLY PERSUASIVE – Without sounding like a speech in a political debate, it must convince the reader by its form, content, and style that the writer is a competent engineer who knows that the facts and conclusions presented are both accurate and important.
To meet these requirements of complete communication, your reports must make extensive and effective use of words. They will, of course, also contain graphs drawings, tables and mathematical demonstrations (and these must be well prepared in all respects); but the reports must use words to introduce, qualify, and interpret the facts presented and to keep the reader moving smoothly from point to point. The words must weave the various parts of the report into a single, coherent whole, so that the report can take readers in hand at the beginning and guide them through the mass of detail assembled during the course of an investigation.
Success in your career may depend on your ability to write successful reports. This is why we ask you to practice writing special reports in this course and why they are carefully reviewed by your instructor.
In reading and grading your reports, your instructor will consider three major areas of your report writing ability: A. Presentation 30% B. Exposition and Execution 30% C. Technical Competence 40%
On the last page of this guide we expand on each of these and state explicitly what we are looking for in your reports. Note that 60% of the grade is based on matters which, superficially, are non-technical. A closer look, however, reveals that almost all of the items under A and some under B require, for a competent job, a clear conception of the technical aspects of the problem. You must perceive what is important about your study to properly organize your report. Your perception of the problem must be so clear that you are able to select the proper words, define physical quantities with precision, and clearly state significant interpretations of your observations.
Note also our heavy demand for good judgment. You must take care that your recommendations on technical matters are responsible and sound. Further, considerable judgment is required in selecting from among the many items of apparent importance those that are significant and meaningful to the reader. For example, after struggling with and finally overcoming certain experimental difficulties, you may feel a compelling desire to relate these important matters to the reader. Indeed, these matters are crucial to the success of your experiment, but readers are seldom interested in a blow-by-blow account. They assume you have removed all serious deficiencies and that you are now reporting on the finished work.
A good way to test a report before handing it in is to read it aloud. Often the ear will catch mistakes, weaknesses, or inconsistencies, which the eye has missed. If your report meets the qualifications briefly outlined above, it should sound like a consistent piece of work from beginning to end.
Finally, reports are graded at their face value. A separate grade is given for you performance in the laboratory. We will assess your laboratory performance by watching to see that you, 1) have perspective on our job and can tell which are the more important parts of it, 2) plan skillfully, budgeting your time to get the most important parts done in the time limitations inevitably present in any job, 3) apply technical skills properly, and 4) work well with your colleagues and your supervisor.
The next section of this guide describes in detail the major parts of a typical report. Several features, such as the abstract, summary, conclusions, nomenclature and references will appear in virtually all reports. However, other major sections should be given descriptive titles, which will be informative to the reader scanning your table of contents. You should not pour the contents of your study into a rigid format, but rather consider each report on its own and devise the best format for its presentation.
Reports are to be typewritten (double-spaced) or neatly penned in ink. Please don’t skimp on paper; allow adequate margins for binding purposes. Fasten your report together securely with brads. Begin each major section on a new page. Number your pages.
Title Page On a separate page indicate the following information:
a) Title of the report;
b) Name of the person submitting it and names of co-workers;
c) Name of school, department and course for which the report is submitted;
d) Name of person or persons to whom the report is submitted;
e) Date.
Abstract In 3 or 4 uninvolved sentences of moderate length state;
a) What was done and with what objectives;
b) Your major results and principal conclusions. Detail must be omitted, but mention must be made of the key features of your work. From this readers will know whether the material contained in the remainder of the report is of interest or usefulness to them in their work. The abstract must be written to stand alone. Write it last. Table of Contents
List the headings of the important parts of the report and the page numbers on which they may be found. This list serves as an outline of the report. Include all headings and subheadings used in the report with wording identical to that used in the report itself. As with an outline, be sure that the headings and subheadings are logically parallel and arranged symmetrically on the page. List all the tables and figures in a separate list headed “Tables and Figures.” Identify each table and figure by number and specific title, and list the page number on which each can be found. Summary The Summary presents in highly condensed form (one page or less) the essentials of
the entire report: your objectives, what you did, and your significant findings. The Summary differs from the Abstract mainly in the amount of detail on the latter two points. In industry the Summary is often the only part of a report read by some readers. Thus it must be written to stand alone, without reference to any other section of the report, just as if it were a separate, miniature report in itself. The Summary should be written after completing the body of the report.
You must exercise judgment in composing the Summary to include only important and relevant information. Avoid trivia. You needn’t include minute details of your experimental technique, unless there is something exceptionally novel about it. Readers will assume you have properly performed the experiment, used suitable methods of measurement and analysis, used a sufficient number of runs, made proper calculations, etc. Such details are more properly included in other sections of the report, not in the Summary.
In reporting results in the Summary it is helpful to state the order of magnitude including units and observed trends. Indicate also whether or not your experimental results agree with the results of some theory or with established correlation. If your results are in disagreement, you might state briefly the reasons for the disagreement. Incidentally, it goes almost without saying that you should compare your results with published results whenever possible. You need not make a major point of this when stating your objectives; it is understood that you will make these comparisons.
It is important to include in your Summary a statement of your significant conclusions. A summary without a statement of conclusions lacks a “punch line.” Be selective in this regard. Seek valid generalizations without overgeneralizing. Above all, be honest. If your experiment proceeded badly and permitted no firm conclusions, so state.
The next sections constitute the body or detailed report. These sections are for the reader who wishes to follow your investigation point by point. Introduction A clear introduction is the key to a good report. It not only presents the essential facts about the purpose of the experiment, but also sets the tone and point of view of the entire report. It is the real beginning of the report proper; it should, therefore, identify the experiment and give a full explanation of its specific aims. It should suggest to readers by its tone and style that they are now to be guided through a detailed report.
Try to state the purpose of the work in logically complete units of thought. That is, do not say, “The purpose of this study was…Another purpose was…Also, the values were to be…” If you cannot state all the purposes in one sentence, begin with a general statement that covers the entire purpose, and then go on to details, or begin with a general statement of the chief purpose, and then go to secondary purposes. In subsequent sections (Results, Discussion, and Conclusions) refer to these topics in the same order in which they appear in the Introduction. Note that all projects in this course are designed to teach you something and to help you become familiar with the operation of equipment. This generation purpose is assumed; do not mention it in the statement of the problem. Instead, explain the specific aims of the work. Such a discussion should give readers a firm grasp of what you are about to lay before them. Specifically, you should consider relating your study to other possible studies in
the same area. Tell your reader how your study fits in among the many that might be made.
In this course you may assume that your audience is composed of people who are technically trained. They will know, for example, the definition of a heat transfer coefficient, the log mean temperature driving force and, indeed, the limitations of such approaches. It is, therefore, out of place for you to attempt to tell the reader how important packed-tower absorption is to the chemical industry and your fellow man. Your reader already appreciates such matters. Neither is your reader interested in the recital of separation processes, for example, which might be used as alternatives to the distillation process you happen to be studying. Remember that you are not writing (nor, hopefully, copying) a textbook. Your report has a far more specific goal and straying from this goal will tend to bore the reader.
Finally, this section of the report should outline briefly your approach to the problem. You should preview for readers how you are about to lead them through the many pathways in pursuit of your goals.
We might reflect a moment on our progress at this point. The first three sections of the report each contain information, which, on first glance, may appear to be identical in all three sections. Granted, there is a high redundancy; we purposely recommend this because the Abstract and Summary are often read separated from the report. The Introduction, while it retreads much of the ground already covered in the Summary, is nevertheless quite distinct and makes important advances into the reporting of your work. It presents a philosophy, an approach, and an insight. The Summary, which must be factual, cannot easily take on these qualities. All three sections are necessary and must be skillfully composed to prepare the reader adequately for the remainder of the report. Experimental Design, Apparatus and Procedure The reader will be interested to learn how you have linked the treatment of the problem discussed in the preceding section to the real world. Your choice of the type of experiment, the variables considered, their ranges, etc., was, of course, determined long before performing the experiment; it is now simply a matter of justifying your decisions in writing. In this discussion you should be careful to relate your considerations in terms of basic variables, not laboratory variables. For example, quote values of Reynolds numbers rather than flow rate. The latter will have no meaning to the reader. It is desirable to summarize the results of your deliberations on the design of the experiment by stating what ‘runs’ were actually made. This might be accomplished conveniently in the form of a table or diagram.
Even though you may have mentioned certain features of the apparatus in previous sections of the report, you should give here a description of all the essential details of the apparatus. In describing apparatus move from the general to the particular; i.e., give the reader first a general description or explanation before going into details. Describe major equipment first; mention minor pieces of equipment at the end. You need not include stock items such as stopwatches and buckets. Secondary details such as tabulation of dimensions or properties of fluids used might be appended if such information is judged necessary for the report. You might be assisted in this discussion by referring to a diagram of the apparatus or some part of it. Diagrams
neatly drawn in either pencil or ink are acceptable. Refer to diagrams by figure numbers; put them immediately following the place where they are first referred to. A schematic block-flow diagram is preferable to a drawing, which attempts photographic accuracy.
Like the description of apparatus, the explanation of procedure should be sufficiently detailed to enable the reader to judge the adequacy of your approach to the problem. In general this means that readers should be able to duplicate your procedure at some future time. You should not, however, go into elaborate details involving routine operations of equipment. Your readers are not interested in a blow-by-blow historical recounting of what happened in the laboratory the day you performed the experiment. Rather, they are concerned about the aspects of your experimental procedure that are not self-evident. For example, how did you measure the height of liquid on the bubble tray and what criterion did you use to establish the condition of flooding in the packed column? Calculation Procedures The purpose of this section of the report is to outline for the reader the basic principles employed and the manner in which they are combined to achieve you objectives. This section is the bridge that shows how the data collected (as described in the Procedure section) leads to the results presented in subsequent sections. For example, by employing a heat balance, you might develop an expression for the condensing film coefficient for heat transfer (which can’t be measured directly) in terms of the measured condensate flow rate and cooling water temperatures. It is good practice to tell the reader in a few sentences what relationships you are about to develop in this section. Be sure to indicate and comment on the significance of your derived results. Otherwise, the reader is likely to pass by them unaware of their utility.
Sometimes the relationships you discuss here are so well known that no derivation is required (e.g., the over-all heat transfer coefficient in terms of individual resistances or the log-mean temperature difference). Usually, however, some development is necessary. In presenting these, it is best to outline the derivations only, stating such equations as you think necessary for the reader’s understanding. Of course, you should give adequate documentation of your sources of information. This is the place also to state any assumptions. It is quite easy, then, to point to possible limitations of your development and deviations of your derived results from the real situation.
Use a separate line for equations. Unless you are an accomplished typist, it is probably best to pen equations by hand. You might number certain equations for ease in referring to them in the text. Results This section presents the final results of the experiment. It usually will contain one or more clear, readable tables and all important graphs. You must use some judgment here in deciding how much detail to present. The primary goal of this section is to inform the reader of the basic behavior of your apparatus or the fundamental nature of the phenomenon under observation. Raw, unreduced data are not “results.” If you feel detailed tabulations are necessary, put them in the Appendix.
It is much easier to see trends in results if you use graphs rather than tables. Graphical comparison of your results with published correlations plotted on the same sheet of graph paper is an effective way to show agreement or disagreement. Be sure that each table and figure has a caption consisting of its number and title. Label all coordinates of graphs in precise unambiguous words or symbols and state units. Use a reasonable number of digits in the numbers in tables; use of too many digits obscures the significance. It may be useful to show the limits of uncertainty for a few entries in tables and graphs to give the reader an estimate of the significance of the results.
To preserve continuity in your report, do not allow this section to stand alone simply as a group of table and graphs. Your purpose is to guide readers through the report; you should not abandon them now. You must comment on you results as they are presented, but this comment must be short of elaboration and interpretation. To effectively communicate your results to readers, you must tell them in words what they are viewing. State, for example, that the plot shows a linear increase of A with B, or note that the heat flux reaches maximum of 500, 000 But/hr ft2 at a T of 50 oC, or point out that your experimental results lie within 25% of Leva’s correlation plotted in Figure 3, and so on. Discussion of Results This section and the preceding one form the heart of the report. Everything you have done and discovered has led step by step to this section. Now you must explain to the reader what your results are and what they mean. Naturally the prime interest will be in the most important results and you should elaborate on this first. Your readers are interested in reading how you interpret your results in a light of the physical and chemical phenomena at play. They will not be interested in a run-by-run account of why the results of Run 3 are high. Instead they expect you to discuss any abnormal behavior, to explain why your results failed to show well established or expected effects, and to indicate how well your results compare with the published results of others.
In this section, you should also discuss the uncertainty in the results. You should point out the probable sources of error and estimate their magnitudes. At this point in the report you should mention only the one or two variables, which contribute the most to the uncertainty and how these uncertainties affect the validity of your final results and conclusions. Be sure that the trends you note in the results and the differences from theory you mention are significant (i.e., larger than the uncertainty). You may also want to discuss shortcomings either in the design of the apparatus or in your performance of the experiment, which could have adversely affected your results.
Finally, the reader would like to have your recommendations concerning the application of your results. You might outline how the reader could apply your information to solve some specific problems. You should also give your opinion concerning the ranges over which your results may be extrapolated safely.
The importance of a balanced discussion of results cannot be overemphasized. Remember that your readers have not “lived” with the results as closely as you have; facts that seem painfully obvious to you may not be obvious to them at all. Your first job is to point them out to him. If you were giving a talk, you
would point to the tables and graphs and explain what they mean, and that is exactly what you should do here. Don’t jump into details until you are sure that readers see the broad trends. Conclusions You, as the planner, experimenter, and writer, are probably one of the persons most qualified to draw conclusions from your work. Even though certain conclusions may seem to you to be so obvious that they should be grasped immediately by the reader, you should nevertheless set down here explicit and unambiguous statements of the major conclusions that you have reached in the discussion section. Readers familiar with your area of study often turn directly to your statement of conclusions; for them, this section often conveys more information than the Abstract or Summary. For the reader of the full report, this section should restate in one location the several conclusions possibly already developed but scattered elsewhere earlier in the report.
Statements in this section require careful judgment. There may be many conclusions that can be drawn; you are to judge which of these are significant enough to be mentioned and which should be mentioned first. Poor judgment is demonstrated in concluding, for example, that the experiment was a success because the data plotted smoothly on semi-log paper. Further, take care to distinguish conclusions from a mere restatement of your experimental results. For example, your experimental results may have indicated that the Fanning friction factor varies with the Reynolds number raised to the (-0.2) power. But a fact many times more important is that the Reynolds number is indeed the only fundamental independent variable (aside from the roughness factor) upon which the friction factor depends. This is an example of a conclusion so obvious that one would hardly consider making the statement, yet to the reader it is not always so obvious. If your work had actually demonstrated this point, then the latter statement should constitute your conclusion. You might add for completeness that the friction factor varies with the Reynolds number raised to the (-0.2) power.
Above all, be scrupulously honest in all your statements. This is often more difficult than it would first appear. Sometimes there are no significant conclusions because of failure to obtain reliable measurements. In such instances, do not generate fictitious conclusions; rather glean from your experiment only those results and conclusions which you think sound. In other cases, you may be unaware that your conclusions are not really justified. For example, in the friction factor study referred to above, you would not be justified in concluding that the Reynolds number was the only independent variable had you varied only the flow rate of water through a ½-inch pipe. You may have been so accustomed to using the Reynolds number in place of flow rate as the independent variable that you may have forgotten that pipe diameter and fluid viscosity must also be varied to adequately test your conjecture. Examine your statements closely for such overgeneralizations. Appendix This section is used as a repository for any details that you think necessary for the completeness of the report. For this course, we ask that you include at least the following two sections:
a) A complete set of sample calculations (these may be neatly lettered in ink) b) The original data sheets (not recopied from the original)
Other details such as tabulation of dimensions of the apparatus, calibration curves and details of the derivation of equations might be included if judged necessary. We comment below on the sample calculations.
Sample calculations are to be included for the purpose of displaying in a clear unambiguous manner you route to the numerical results that are quoted in the report. Actual numerical values of quantities, taken from one of your experiments, are to be substituted into whatever equations apply and the numerical result stated. To do a good job at this, you need to prepare a well-organized, logical structure that considers the reader’s unfamiliarity with some of your techniques. It is suggested that you use descriptive subheadings to announce the calculations you are about to describe. Before launching into the calculation, state in a few sentences what you intend to calculate (and, if necessary, why) and what physical principles are to be employed. Even though you may have treated these matters in an earlier section, a brief recollection at this point is appreciated by the reader. Then quote the equation to be used. If you have discussed this particular relationship earlier in the report, you need only refer to that discussion and may pass on directly to the substitution of numerical values. If you have not previously discussed the relationship, this is the place to do so.
It is further suggested that calculations of the most important quantities precede those of less importance. If possible place calculations of modified Reynolds numbers, void fraction, particle density, and other such minor calculations at the end. Nomenclature In technical writing, it is usually most convenient to define in one place in all symbols and notation used throughout the report even though these symbols will have been defined in the text at the point where they were first introduced. The common practice is to list in alphabetical order all symbols used in the report with a descriptive definition of their meaning or interpretation including statement of units used. It is adequate to merely state that hO is a heat transfer coefficient for condensing vapors based on the outside area of tubes, Btu/hr ft2 oF.
You may view our request that you include this section as an unjustified and unnecessary demand on your time. Granted that the alphabetical arrangement is tedious; however, the necessity to make definite and precise definitions of terms is good practice and often is instrumental in uncovering errors. References Another common and convenient practice is to list at the end of the report all established literature specifically referred to in the text. Note this is not a bibliography of literature that you looked at in preparation for your study, but rather specific citations made in the text of your written report. Normally, a number identifies each reference. You may refer to individual references in the body of the simply by stating the reference identification number in parenthesis. For example, “…as shown by the Miller and Michels correlation (7).” All references should be arranged in alphabetical
order, based upon the name of the first author mentioned. The following are some examples of good form.
Journal Article I.A. Wishe and E.B. Bagley, Thermodynamic Properties of Solutions of Alcohols in Inert Solvents, Ind. Eng. Chem. Fundamentals 6 [2], 209 (1967) The title is optional, but it is often helpful when your reader is attempting to use your report to compile a literature survey. The number is square brackets, the issue number, is often not necessary. Book Stanley Middleman, The Flow of High Polymers, (Interscience Publishers, New York, 1968). Ch. 2, pages 360-365. Article in a Book John W. Bartlett, Stuart McLain and Owen H. Gailan, Nuclear Engineering in Engineering Manual, 2nd Edition, Robert H. Perry, ed., (McGraw-Hill Book Co., New York, 1967), Section 9.
In referring to a book be as specific as possible. Noting the edition, section, and page number is a necessity. If you use a the internet as a reference, the complete URL must be provided, e.g., CHEMICAL ENGINEERING LABORATORY CONSIDERATIONS FOR GRADING REPORTS
A. Presentation (30 percent)
1. Organization: The assembly of information and facts into a logical and understandable sequence of statements leading to definite objectives and conclusions.
2. Logical coherence of the parts.
3. Completeness:
Inclusion of absolute essential as a minimum. Judgment in omission of irrelevant, non-essential and trivial material. Discussion of important materials not necessarily self-evident, such as discussion of limitations of equipment and recommendations of improvement.
4. Judgment concerning importance of material discussed (exemplified by
the material discussed, order of presentation, direct statements of importance, length of presentations, etc.)
B. Exposition and Execution (30 percent) 1. Clarity 3. Economy of Words 5. Spelling 2. Precision 4. Grammar 6. Neatness C. Technical Competence (40 percent)
1. Correctness and clarity of thought concerning the relevant physical and chemical phenomena at play.
2. Treatment of data – soundness of methods and novelty in using experimental data to obtain objectives and arrive at conclusion.
3. Calculations – proper treatment and presentation of calculations, numerical preciseness, clarity of presentation.
4. Quality of results – a reflection on the quality of experimental techniques, design of the experiment, treatment of data, and calculations.
5. Conclusions – the recognition and interpretation of the significance on the information presented. Judgment in stating technically sound conclusions, judgment in stating the most important conclusions first; and judgment in omission of trivia.
1. Objective, results, and conclusions must be prominent. 2. Information content per sentence. 3. Completeness in stating the bare essentials of your work. 4. Judgment concerning what is to be included and what is to be omitted. 5. Organization – order of presentation. 6. Exposition – clarity, precision economy, grammar, spelling.