3. Materials and methods

Function: In this section you explain clearly how you carried out your study in the following general structure and organization (details follow below):

• the object(s) studied (reservoir, petroleum product, drilling equipment, etc.) and their pre-experiment handling and care, and when and where the study was carried out (only if location and time are important factors); note that the term "subject" is used ONLY for human studies.

• if you did a field study, provide a description of the study site, including the significant physical and biological features, and the precise location (latitude and longitude, map, etc);

• the experimental OR sampling design (i.e., how the experiment or study was structured. For example, controls, treatments, the variable(s) measured, how many samples were collected, replication, the final form of the data, etc.);

• the protocol for collecting data, i.e., how the experimental procedures were carried out, and,

• how the data were analyzed (qualitative analyses and/or statistical procedures used to determine significance).

Style: The style in this section should read as if you were verbally describing the conduct of the experiment. You may use the active voice to a certain extent, although this section requires more use of third person, passive constructions than others. Avoid use of the first person in this section. Remember to use the past tense throughout – the work being reported is done, and was performed in the past, not the future. The Methods section is not a step-by-step, directive, protocol as you might see in your lab manual.

Here is some additional advice on particular problems common to new scientific writers.

Problem: The Methods section is prone to being wordy or overly detailed.

• Avoid repeatedly using a single sentence to relate a single action; this results in very lengthy, wordy passages. A related sequence of actions can be combined into one sentence to improve clarity and readability:

Problematic Example: This is a very long and wordy description of a common, simple procedure. It is characterized by single actions per sentence and lots of unnecessary details.

"The petri dish was placed on the turntable. The lid was then raised slightly. An inoculating loop was used to transfer culture to the agar surface. The turntable was rotated 90 degrees by hand. The loop was moved lightly back and forth over the agar to spread the culture. The bacteria were then incubated at 37 C for 24 hr."

Improved Example: Same actions, but all the important information is given in a single, concise sentence. Note that superfluous detail and otherwise obvious information has been deleted while important missing information was added.

"Each plate was placed on a turntable and streaked at opposing angles with fresh overnight E. coli culture using an inoculating loop. The bacteria were then incubated at 37 C for 24 hr."

Best: Here the author assumes the reader has basic knowledge of microbiological techniques and has deleted other superfluous information. The two sentences have been combined because they are related actions.

"Each plate was streaked with fresh overnight E. coli culture and incubated at 37 C for 24 hr."