Writing your first paper: Step Four: The Introduction
Sorry it has taken me so long to get to the next installment. I'm afraid the remainder may be slow in coming as well. I am currently in the midst of preparing for conferences and getting data together for a paper. On the positive side, everything is working!
This article is part of a series on writing your first research paper. I am hoping to use this material for a new student handbook when I start my faculty position, so any thoughts, comments, hysterical rejoinders are most welcome.
Note- All data for the ice cream example is made up. However, you really can make ice cream using liquid nitrogen.
Next to the abstract, this is the most important part of your paper. This is your chance to get your audience interested in your topic and encourage them to read the rest of your paper. When researchers prepare review articles and book chapters they will read your introduction to figure out what you did, why you did it, and why its neat, and then will read your conclusions/discussion to figure out the broader implications. In many cases readers will only glance at the figures in the results section and skip materials and methods altogether. It is therefore critical that your introduction be concise, readable, and interesting.
In general the introduction should contain three sections:
1. What is the problem and why are you working on it?
2. What did you do?
3. Why is this better than previous approaches?
What is the problem and why are you working on it?
This portion of the introduction should include 1-2 paragraphs and is your opportunity to attract your reader. You not only have to explain what the problem is and why it is important to you, but also convince your reader that they should care about it too. Using our ice cream example, I would first motivate the problem in a broad context:
Every year over 10 million people make ice cream at home using hand crank and electric ice cream machines., representing a sales market of over 50 million dollars . However, hand crank machines require several pounds of messy and potentially toxic rock salt. Ice cream does not form for several hours and requires constant cranking to retain a uniform texture . To address these issues, manufacturers have developed electric ice cream machines that do not require rock salt and reduce freezing time to 20-30 minutes , but these machines are not as promising as they would seem. Electric ice cream makers use canisters to maintain low temperatures. These canisters must be placed in the freezer overnight prior to making ice cream. Thus, the user must plan at least 1 day in advance before making ice cream . Additionally, if ice cream is not to be eaten immediately, the ice cream precursor must be manufactured and refrigerated overnight to obtain the best texture . Although electric ice cream makers would seem to shorten the manufacturing process, they in fact require a substantial input of user time and planning.
The first sentence tells the reader that they should care about this because lots of people make ice cream at home and the market for ice cream makers is large. The next few sentences explains how people are currently making ice cream at home and the flaws inherent in that process. We are setting the reader up for the next paragraph: what I did, which presumably addresses these issues. [Citations are given in brackets and will be discussed separately in another post]
What did you do?
Keeping in mind that most people will not read your materials and methods section, explain in 1 paragraph, or 2 if particularly complicated, what you did. Use a minimum of jargon, remember you are trying to draw in readers who might be in different disciplines and unfamiliar with terms, but make it technical enough that it is not condescending. Also, always define abbreviations before using them throughout the text, even if they are well-known in your field. There is nothing more frustrating than having to google an abbreviation to figure our what it means.
To address these issues, we have developed a rapid freezing process for making well-textured ice cream using liquid nitrogen (LN2) as a freezing medium. We evaluated the speed of freezing, comparing it to that of traditional hand crank and electric machine methods. Additionally, we evaluated ice cream texture of LN2 and control mixtures using blind taste tests, viscometry to assess smoothness, and measured air content. Finally, we developed a prototype-home ice cream maker to safely produce ice cream in a home environment.
The first sentence gives a summary of what we did. If you only read this sentence, you would get the gist of this paper. The following sentences describe the specific analyses that we performed to characterize our method, without disclosing specific data, which belongs in the results section. These sentences are arranged in the order that data will be presented in the results section. No conclusions are drawn about the superiority of our method here. This paragraph is straight information.
Why is it better than previous approaches?
Here is where you bring it home. You have convinced the reader that you are working on an important problem. You have outlined your solution in an unbiased descriptive paragraph. Now is the time to say why what you did is far better than existing methods.
Our method demonstrates an improvement in current home ice cream technologies that may increase marketplace appeal, especially to time-crunched professionals. Liquid nitrogen ice cream was produced in dramatically shorter times than traditional methods, with little prior planning required. Texture and quality was superior or equal to traditional methods. Although liquid nitrogen may present safety issues in a laboratory context , our home ice cream prototype addresses these concerns, rendering LN2 technology safe for the masses. While originally designed for ice cream, this technology may also be used to manufacture a number of frozen treats, including sorbets, sherberts, slushies, frosties, and italian ices.
The first sentence is the most important conclusion for the reader. We have developed a method that may increase marketplace appeal, especially to a desirable target group. The next few sentences support the claim made in the first sentence. Then, limitations of our technique are discussed (i.e., safety) and addressed. This is really important, because it is your chance to address your critics. Don't wait for the reviewer to ask! If you know there is a possible problem with your technique, a hole in your data, or potentially better method, this is your chance to argue your case. Finally, the work is placed in the broader context. This technology applies not only to ice cream, but possibly to other areas as well. The last sentences are your chance to grab those readers from other areas that might be interested in your technique, but don't work in your area directly. You are in the best position to envision all possible applications of your research. This is your chance to talk about them.