An appendix contains supplementary material that is not an essential part of the text itself but which may be helpful in providing a more comprehensive understanding of the research problem or it is information that is too cumbersome to be included in the body of the paper. A separate appendix should be used for each distinct topic or set of data and always have a title descriptive of its contents.
Tables, Appendices, Footnotes and Endnotes. The Writing Lab and The OWL. Purdue University.
Appendices are always supplementary to the research paper. As such, your study must be able to stand alone without the appendices, and the paper must contain all information including tables, diagrams, and results necessary to understand the research problem. The key point to remember when including an appendix is that the information is non-essential; if it were removed, the reader would still be able to validity your research.
It is appropriate to include appendices for the following reasons:
Appendices. Academic Skills Office, University of New England; Chapter 12, "Use of Appendices." In Guide to Effective Grant Writing: How to Write a Successful NIH Grant. Otto O. Yang. (New York: Kluwer Academic, 2005), pp. 55-57; Tables, Appendices, Footnotes and Endnotes. The Writing Lab and The OWL. Purdue University.
I. General Points to Consider
When considering whether to include content in an appendix, keep in mind the following:
Never include an appendix that isn’t referred to in the text. All appendices should be summarized in your paper where it is relevant to the content. Appendices should also be arranged sequentially by the order they were first referenced in the text [i.e., Appendix 1 should not refer to text on page eight of your paper and Appendix 2 relate to text on page six].
There are very few rules regarding what type of material can be included in an appendix, but here are some common examples:
NOTE: Appendices should not be a dumping ground for information. Do not include vague or irrelevant information in an appendix; this additional information will not help the reader’s overall understanding and interpretation of your research and may only distract the reader from understanding the significance of your overall study.
ANOTHER NOTE: Appendices are intended to provide supplementary information that you have gathered or created; it is not intended to replicate or provide a copy of the work of others. For example, if you need to contrast the techniques of analysis used by other authors with your own method of analysis, summarize that information, and cite to the original work. In this case, a citation to the original work is sufficient enough to lead the reader to where you got the information. You do not need to provide a copy of this in an appendix.
Here are some general guideline on how to format appendices. If needed, consult the writing style guide [e.g., APA, MLS, Chicago] your professor wants you to use for more detail:
Appendices. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Appendices. Academic Skills Office, University of New England; Appendices. Writing Center, Walden University; Chapter 12, "Use of Appendices." In Guide to Effective Grant Writing: How to Write a Successful NIH Grant. Otto O. Yang. (New York: Kluwer Academic, 2005), pp. 55-57; Tables, Appendices, Footnotes and Endnotes. The Writing Lab and The OWL. Purdue University; Lunsford, Andrea A. and Robert Connors. The St. Martin's Handbook. New York: St. Martin's Press, 1989; What To Know About The Purpose And Format Of A Research Paper Appendix. LoyolaCollegeCulion.com.
Consider Putting Your Appendices Online
Appendices are useful because they provide the reader with information that supports your study without breaking up the narrative or distracting from the main purpose of your paper. If you have a lot of raw data or information that is difficult to present in textual form, consider uploading it to an online site. This prevents your paper from having a large and unwieldy set of appendices and it supports a growing movement within academe to make data more freely available for re-analysis. If you do create an online portal to your data, note it prominently in your paper with the correct URL and access procedures if it is a secured site.
Piwowar, Heather A., Roger S. Day, and Douglas B. Fridsma. “Sharing Detailed Research Data Is Associated with Increased Citation Rate.” PloS ONE (March 21, 2007); Wicherts, Jelte M., Marjan Bakker, and Dylan Molenaar. “Willingness to Share Research Data Is Related to the Strength of the Evidence and the Quality of Reporting of Statistical Results.” PLoS ONE (November 2, 2011).