WRITING THE MATERIALS AND METHODS SECTION

1.0 INTRODUCTION

In the first section of your technical report or paper, the Introduction, you stated (or should have) the methodology employed in the study: If necessary, you also defended the reasons for your choice of a particular method over competing methods.

Now in Materials and Methods, you must give the full details. The main purpose of the Materials and Methods section is to provide enough detail that a competent worker can repeat the experiments or field surveys. Many (probably most) readers of your paper or report will skip this section, because they already know (from the Introduction) the general methods you used and they probably have no interest in the experimental detail. However, careful writing of this section is critically important because the cornerstone of the scientific method requires that your results or findings, to be of scientific merit, must be reproducible. And, for the results to be adjudged reproducible, you must provide the basis for repetition of the experiments or field surveys by others. That experiments are unlikely to be reproduced is beside the point; the potential for producing the same or similar results must exist, or your paper does not represent good science.

This unit, then, is divided into six sections. The first section tells you how to handle the Materials part of your report and the second the Methods part. The remaining five sections deal with other specific aspects of Materials and Methods that scientists, especially beginning scientists, usually find troublesome: Headings and Sub-headings

(section five), Measurements and Analysis (section four), the presentation of certain Tabular, Material (section five), and the use of correct Form and Grammar (section six). The usual 'Conclusion', 'Summary', and 'References' sections complete the unit. Two Self-Assessment Exercises are embedded in the text.

3.0 MAIN CONTENT

3.1 Materials

For materials, you must include the exact technical specifications and quantities, as well as the source(s) and method(s) of .preparation. Sometimes it may even be necessary for you to list pertinent chemical and physical properties of the reagents used. You should avoid the use of trade names; use of generic or chemical names is usually preferred. This avoids the advertising inherent in the trade name. Besides, the nonproprietary name is likely to be known throughout the world, whereas the proprietary name may be known only in the country of origin. However, if there are known differences among proprietary products and if these differences may be critical (as with certain microbiological media), then the use of the trade name, plus the name of the manufacturer, is essential.

Experimental animals, plants, and microorganisms should be identified accurately, usually by genus, species and strain designations. Sources should be listed and special characteristics (age, sex, genetic and physiological status) described. If human subjects are used, the criteria for selection should be described, and an "informed consent" statement should be added to the manuscript, just in case it might be required. Because the value of your report or paper (and your reputation) can be damaged if your results are not reproducible, you must describe research  materials with great care. A useful way in which you could learn to do this properly and consistently is to examine several examples of the Instructions to Authors of important journals in your subject area. Such Instructions usually give details of important specifics that are often required in technical reports, too. Below is a carefully worded statement applying to cell lines (taken from the Information for Authors of In Vitro, the Journal of the Tissue Culture Association):

Cell line data: The source of cells utilised, species, sex, strain, race, age of donor, whether primary or established, must be clearly indicated. The supplier’s name, city, and state abbreviation should be stated within parentheses when first cited. Specific tests used for verification of purported origin, donor traits, and detection for the presence of microbial agents should be identified. Specific tests should be performed on cell culture substrates for the presence of mycoplasmal contamination by using both a direct agar culture and an indirect staining of biochemical procedure. A brief description or a proper reference citation of the procedure used must be included. If these tests were not performed, this fact should be clearly stated in the Materials and Methods section. Other data relating to unique biological, biochemical and biochemical and /or immunological markers should also be included, if available.

Evidently, describing materials in the medical sciences probably requires greater detail in certain respects than other branches of science. Whatever your area of specialisation, however, you should get into the habit of describing the materials used in any experiment or field work in as much detail as you possibly can.

*Assemble as many 'Instructions to Authors' of journals in your field as you can. Reproduce the sections describing the Materials for scientific research published. in the journals. Write the Materials sections for two scientific papers or technical reports of your choice. Compare what you have written with those in the published journals.

3.2 Methods

For methods, the usual order of presentation is chronological. However, whenever you have to make a different order of presentation, such as in geomorphology, it is suggested that you make a special case for it. Obviously, related methods should be described together and straight chronological order cannot always be followed. For example, if a particular assay was not done until late in the investigation, you should describe the assay method along with the other assay methods, not by itself in a later part of Materials and Methods.
It is worth repeating here that in describing the methods of investigations, you should give sufficient details so that a competent worker could repeat the experiments. If your method is new (that is, unpublished), you must provide all of the needed detail. However, if a method has already been published in a standard journal, only the literature reference should be given (see also Module 3 Unit 4).

Scientists in developing countries face a serious ethical issue in regard to the use of the words "published in a standard journal" above. What constitutes a "standard journal"? Every answer to this question will have an element of bias as a considerable dose of opinion will be involved. Librarians, and especially information scientists, have evolved fairly objective methods for deciding "best" journals, or the "most frequently cited" journals, or journals with the "highest impact factors", etc. Unfortunately, few journals in developing countries meet the criteria of being among such "best" journals. Consequently, you may have to provide a complete description, in your present Methods section, of the same method that has been previously published in a relatively unknown scientific journal based in a developing country.

However, if the truth must be told, there have been several documented cases of scientists in developing countries publishing the same papers locally and in the so-called prestigious journals. Such practice is a disservice to science in general and to the course of science in developing countries in particular. You have a responsibility not to indulge in such practice, ever. (See Module 2 Unit 4).

3.3 Headings and Sub-Headings 

You must learn to use headings and sub-headings to bring out clearly and logically the components of your investigation. When possible, sub- headings that "match" those to be used in presenting the Results of your investigation should be used in the Materialsand Methods section. In that way, the writing of both sections will be much easier, and the reader will be able to grasp quickly the relationship of a particular methodology to the related Results.

In addition to main headings, you will find the use of a variety of levels of sub-headings helpful as signposts to direct the reader through your report. The best way to learn how to do this is to examine a variety of good journals in your subject area in order to get familiar with how main headings are effectively used with sub-headings to achieve the desired effectYou will notice differences in style as you examine them; what is important is for you to adopt a particular style and learn to stick to it in all your writing. Fortunately for you, the availability of word processing software introduces a large variety of alternative formats for you to choose from, in addition to the routine supply of scientific symbols with such software.

3.4 Measurements and Analysis

Your watchword here is: be precise. If a reaction mixture was heated, give the temperature. You must answer questions such as "how" and "how much" precisely; they must never be left to the reader to puzzle over.


Statistical analyses are often necessary, but you should feature and discuss the data, not the statistics. Generally, a lengthy discussion of statistical methods indicates that the writer has recently acquired this information and believes that the readers need similar enlightenment. In most cases, you should use ordinary statistical methods (the chi-squared test, regression analysis, co-variance, and the like) without comment; advanced or unusual methods may require only a literature citation. However, in many contexts of technical report writing, your analysis of the needs of your target audience may require 'that you provide detailed explanation of even some "ordinary statistical methods." You should be particularly sensitive to such specific needs, especially when certain key  individuals in your target audience may not be too numerate. In which case, your analysis takes on something of the character of marketing your product (the report) to specific clients who must appreciate the value of the product sufficiently to want to buy it.

Finally, in this section, be careful of your syntax. Errors of syntax are among the most common in scientific writing in developing countries where most writers use English as a second language. A major reason is that many writers think first in their mother tongue and then translate the thought process into written English. You can eliminate most errors of syntax in your writing through constant practice and reading standard published literature in your subject area. You have a responsibility of raising the level of your written communication to the level of acceptability as a member of the international community of serious writers in your field (See Module 3 Unit 4.)

3.5 Tabular Material

In Module 2 Unit 5, you will be formally shown how to prepare and use tables in presenting the results of scientific experiments. Here, we are concerned with letting you learn how to present tabular material during
2 the stage of scientific writing before the results. Of course, it is not always as clear cut as that. If you are in any doubt, you should present your tabular material of the kind described here in the Materials and Methods section of your technical report or paper and cite it in the Results section.

When large numbers of microbial strains or mutants are used in a study, you should prepare tables identifying the source and properties of mutants, bacteriophages, plasmids, etc. The properties of a number of chemical compounds can also be presented in tabular form, often to the benefit of both the author and the reader. You can find help in learning how to do this properly and consistently by consulting special manuals or appendixes to standard textbooks in your subject area. Note, however, that a method, strain, etc., used in only one of several experiments reported in your technical report or paper, should be described in the Results section or, if brief enough, may be included as a footnote to a table or a figure legend.

3.6 Correct Form and Grammar

Finally, do not make the common error of mixing some of the Results in the Materials and Methods section of your report or paper. In summary, there is only one rule for a properly written Materials and Methods section: You must give enough information so that your experiments or field surveys could be reproduced by a competent colleague.

A good test, and a good way to avoid rejection of your report or manuscript, is to give a copy of your finished manuscript to a colleague and ask if he or she could repeat the experiments. It is quite possible that in reading your Materials and Methods, your colleague will pick up a glaring error that you missed simply because you were too close to the work. For example, you might have described your distillation apparatus, procedure, and products with infinite care, and then inadvertently neglected to define the starting material or to state the distillation temperature.


Mistakes in grammar and punctuation are not always serious; the meaning of general concepts, as expressed in the Introduction and Discussion (see Module 2 Unit 4), can often survive a bit of linguistic mayhem. In other words, nobody expects you to write a 'perfect' technical report or scientific paper. In Materials and Methods, however, exact and specific items are being dealt with and precise use of English is a must. Even a missing comma can cause havoc, as in the sentence: "Employing a straight platinum wire rabbit, sheep and human blood agar plates were inoculated." That sentence was in trouble right from the start, because the first word is a dangling participle. Comprehension
didn't completely go out of the window, however, until the author neglected to put a comma after "wire".

Because the Materials and Methods section usually gives short, discrete bits of information, the writing sometimes becomes telescopic; details essential to the meaning may then be omitted. The most common error you should watch for in your writing is to state the action without stating the agent of the action. For example, in the sentence "To determine its respiratory quotient, the organism was . . ., the only stated agent of the action is "the organism," and somehow you have to doubt that the organism was capable of making such a determination. Here is a similar sentence: "Having completed the study, the bacteria were of no further interest." Again, you have to doubt that bacteria "completed the study"; if they did, their lack of “further interest” was certainly an act of ingratitude. This kind of grammar error in written scientific discourse described above is found in so-called prestigious journals as in obscure, low-rating ones. This is hardly cold comfort to many journals based in developing countries where English is, invariably, a second language. You are asked to consider the last two samples below as what might happen to your writing, once you become careless with grammar or logic.


"Blood samples were taken from 48 informed and consenting patients . . . the subjects ranged
in age from 6 months to 22 years" (Pediatric Research, 6:26, 1972).

There is no grammatical problem with that sentence, but the telescopic writing has compromised logic, leaving the reader wondering just how the 6-month-old infants gave their informed consent.

And, of course, you must always watch for spelling errors at every stage of your manuscript preparation. It does not require an astronomer to suspect that a word is mispelled in the following sentence:


"We rely on theatrical calculations to give the lifetime of a star on the main sequence" (Annual Review of Astronomical Astrophysics, 1:100, 1963).


Correct the two sentences above. Locate several more examples of errors of grammar or logic or both in the literature of your subject area. Rewrite them correctly and apply what you have learned to the tutor-marked assignment for this Unit.

4.0 CONCLUSION

The Materials and Methods section of a technical report or scientific paper demands that you give such detailed information in it that a competent colleague could repeat the experiments or field surveys. Therefore, you must write it carefully to include exact technical specifications and quantities, as well as the identification of experimental animals, plants and microorganisms by genus, species, and strain designations. For methods, the usual order of presentation is chronological, unless there are exceptional circumstances (which you must state) which demand a different order. You must learn to use headings and subheadings to bring out clearly and logically the components of your investigation, and you must be precise in writing your measurements and analysis. Finally, you must learn to eliminate all errors of form, grammar, syntax, logic, and spelling in the presentation of the Materials and Methods section and, indeed, all sections of your technical report or scientific paper.

5.0 SUMMARY

In this unit, you have learned to:

1.  describe accurately the technical specifications and quantities of the research materials used in your experiments or field surveys;
2.  explain clearly your method(s) of investigation 
3. show precisely how you carried out your measurements and analysis 
4.  defend your presentation of certain tabular material in this section of your report; and 
5.  use correct headings, sub-headings, form, grammar, and syntax in presenting relevant information. 

6.0 TUTOR-MARKED ASSIGNMENT

1.  Describe accurately the technical specifications and quantities of  the research materials used in your experiments or field surveys. 
2.  Explain clearly your method(s) of investigation. 
3.  Show precisely how you carried out your measurements and analysis. 
4. Defend your presentation of certain tabular material in this section of your report.