Writing your first paper: Step Seven: Results-General Comments and Tables
This post is part of a series (that is taking a long time to write) on writing your first research paper. I plan to use this information for my graduate students. So feel free to send your thoughts, comments, and hysterical rejoinders. Also, all data is completely made-up so don't quote me on anything.
In my enthusiasm to discuss figures in the last post, I didn't really give too much information on the results section so I'd like to do that now. The results section is sometimes combined with discussion and in this case the general format would be paragraph presenting results, paragraph discussing implications of results. Otherwise, the results section should only present data, but draw no conclusions as to its meaning. Each experiment should be separated with a header. Data should always be presented in the most unbiased manner possible. If there were inconsistencies explain why if possible, but do not attempt to make excuses for your results. Also, if there was a problem with your assay that limits its meaning, this is a place for discussing that (although this might also be found in discussion). Data should be presented by providing the observation, the standard deviation or variance of the observation, the statistical comparison of this observation to others, and the number of experiments that were used to create the observation. Good experimental design will lead to a good results section. It is important to perform positive and negative controls where possible. Using our ice cream example, a paragraph in the results section might read as follows:
Ice Cream Texture
Ice cream texture was evaluated using a viscometer to measure viscosity and also using a double blind taste test. Viscosity measures the thickness of the ice cream and therefore is a measure of the texture. In general, a thicker texture is preferred, although high viscosity can make consumption difficult (e.g., brick-like consistency).Liquid nitrogen ice cream possessed a similar viscosity to that of store-bought (1.96 +/- 0.05 cp for LN2 vs. 1.85 +/- 0.06 cp for store-bought, t-test p value > 0.05, n=5) and was more viscous to ice cream produced by hand crank (1.24 +/- 0.15 cp) and electric machine (1.01 +/- 0.12 cp).
In the double blind taste test, 100 university students age 18-22 were asked to sample each of four types of ice cream. All ice creams were vanilla flavored, made from the same recipe, only varying in the freezing technique. Students were asked to rate the ice cream for flavor, texture, and the presence of ice crystals on a scale of 1 to 10 with 10 being superb/desirable and 1 being inedible. Results were compiled and analyzed using a student t-test with alpha equal 0.05 (Figure 1). For flavor, all ice creams were rated similarly with an average value of 7.4 +/- 0.09 for liquid nitrogen and no statistical difference between it and the other choices (7.2 +/- 0.1 store-bought, 7.0 +/- 0.05 hand crank, 6.9 +/- 0.07 electric machine). For texture, freezing techniques were preferred as liquid nitrogen > store-bought > hand crank > electric machine, with electric machine ranking far below the other three. The difference between liquid nitrogen and store bought was insignificant ( p > 0.5), but both of these techniques were deemed to produce superior texture to hand crank (p < 0.05) and electric mixer (p < 0.001). Only the electric machine was found to display ice crystals (rating = 2.5 +/- 0.09), whereas the remaining three ice creams displayed ice crystal ratings averaging 8-9.
Notice that this description gives very little discussion. The data is presented, with statistics to aide the reader, and some description of the experiment is given. It is also possible to roll some of the experimental details into materials and methods, but I find that most readers skip this section, so I like to recapitulate the basics in the results section. It is very important to not be judgmental about your data. Simply report what you found.
Finally, a word about tables:
Pretty straightforward. Tables can be created in excel fairly easily. In general, tables should contain a header row, which is separated from the data with a solid line, then the data in columns, then a solid line to separate the data from the bottom of the table, and below that line footnotes as needed. Footnotes typically are used to define abbreviations in the table, describe experimental conditions, and point out outliers. Lines should NOT be used to separate columns.
Well good luck, and soon, I promise, I will post on discussion, references, and finally conclude.