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Types Of Evidence Is Used To Support Opinions In Research Papers

Most of the assignments you will do in university will ask you to make an argument, to take a stance, or to prove a hypothesis. The best way to do this is to research the topic, develop a thesis statement, hypothesis, or claim and then use evidence to support this claim.

Think of evidence as the supports that buttress your claim, making it more solid than it would be alone. In fact, if you make a claim or an argument without evidence, your paper could appear to be unsupported opinion or not particularly well-researched. Even when the assignment elicits opinion, your paper will be more convincing if you provide evidence and the instructor may still be looking for an argument.

This Fastfacts explains what evidence is and how to incorporate it into your writing.

What is Evidence?

Evidence is the facts, examples, or sources used to support a claim. In the sciences, this might be data retrieved from an experiment or a scientific journal article. In the humanities, it may be a quotation from the text, published information from academic critics, or a theory that supports your claims. Evidence can be separated into two categories, primary and secondary sources.

What are Primary Sources?

Primary sources are first-hand experiences, accounts, observations, reports, or narratives. Primary sources could include diaries, letters, contemporary newspapers, or eyewitness accounts of events. Official documents (e.g. the Canadian Charter of Rights and Freedoms), data collected from surveys, and lab results are also primary sources. In the humanities, the text you are writing about is also considered your primary text. So, for example, if you are writing a paper on Macbeth, then the play is your primary source. In the sciences, primary sources are also the results of an experiment that have been peer-reviewed and published in an academic journal.

What are Secondary Sources?

Secondary sources are critiques written by academics and scholars. These sources are considered secondary because they examine primary sources to present an argument or support a point of view; as such, they may be selective with their evidence or insert themselves in a debate happening among a number of scholars. In the sciences, reviews, which are surveys of articles that demonstrate an understanding of a field, are considered secondary. It is a good idea to be aware of the bias in secondary sources when employing them as evidence.

Frequently the assignment will specify whether you need to use primary or secondary sources; however, if you are unsure about what kind of sources you need, ask your professor for clarification.

Among the forms of evidence you might draw from are:

  • Graphs, charts, tables, or figures
  • Statistics
  • Experiments or studies done by peer-reviewed sources
  • Surveys conducted by reputable sources
  • Interviews
  • Quotes or paraphrases from primary sources
  • Quotes or paraphrases from secondary sources

NOTE: In general, you should not use quotes in science papers.

How Do I Use Evidence?

Standards for Evidence

Each discipline and each genre of writing will have standards against which it will gauge the academic merit and use of evidence. But some general rules apply (a detailed explanation of each rule follows this list):

  • Make sure your evidence is appropriate to the paper you are writing
  • Make sure the evidence does, in fact, support your argument or your claims
  • Tell your reader why this evidence supports your argument/claims
  • Make sure you have an appropriate amount of evidence
  • Make sure to appropriately cite your evidence

NOTE: Though not a general rule, your paper will be strengthened by acknowledging competing evidence – evidence that challenges your argument. This demonstrates that you have fully researched your topic and can counter claims against your argument.

Selecting Evidence

Much of how to use evidence is about finding a clear and logical relation between the evidence you use and your claim. For example, if you are asked to write a paper on the effects of pollution on watersheds, you would not use a story your grandfather told you about the river he used to swim in that is now polluted. You would look for peer-reviewed journal articles by experts on the subject.

Once you have found the appropriate type of evidence, it is important to select the evidence that supports your specific claim. For example, if you are writing a psychology paper on the role of emotions in decision-making, you would look for psychology journal articles that connect these two elements.

For example:

Emotions play a larger role in rational decision-making than most us think. (claim) Subjects deciding to wear a seatbelt demonstrated an activity in the ventromedial frontal lobe, the part of the brain that governs emotion (Shibata 2001). (evidence) Or, if you are asked to write a paper on the gothic elements of Dr. Jekyll and Mr. Hyde, you might use as evidence a quote or two from the text itself.

For example:

The physical descriptions of the laboratory and the main house, in Dr Jekyll and Mr. Hyde, metaphorically point to the gothic elements in the novel. (claim) The main house had "a great air of wealth and comfort" (13) while the laboratory door "which was equipped with neither bell nor knocker, was blistered and distained." (3) (evidence)

By referencing the study in the first example and supplying textual evidence in the second, the initial statement in the paragraph moves from opinion to supported argument; however, you must still analyze your evidence.

Analyzing Evidence

Once you have selected your evidence it is important to tell you reader why the evidence supports your claim. Evidence does not speak for itself: some readers may draw different conclusions from your evidence, or may not understand the relation between your evidence and your claim. It is up to you to walk your reader through the significance of the evidence to your claim and your larger argument. In short, you need a reason why the evidence supports the claim – you need to analyze the evidence. Some questions you could consider are:

  • Why is this evidence interesting or effective?
  • What are the consequences or implications of this evidence?
  • Why is this information important?
  • How has it been important to my paper or to the field I am studying?
  • How is this idea related to my thesis?
  • This evidence points to a result of an experiment or study, can I explain why these results are important or what caused them?
  • Can I give an example to illustrate this point?
  • What are the strengths and weaknesses of the evidence presented?

If we look to our first examples, they may look like this once we add analysis to our evidence:

Emotions play a larger role in rational decision-making than most us think. (claim) Subjects deciding to wear a seatbelt demonstrated an activity in the ventromedial frontal lobe, the part of the brain that governs emotion (Shibata 2001). (evidence) This suggests that people making rational decisions, even when performing naturalized tasks such as putting on a seatbelt, rely on their emotions. (analysis)

Or, when we look at the example of Dr. Jekyll and Mr. Hyde:

The physical descriptions of the laboratory and the main house, in Dr Jekyll and Mr. Hyde, metaphorically point to the gothic elements in the novel. (claim) The main house had "a great air of wealth and comfort" (13) while the laboratory door "which was equipped with neither bell nor knocker, was blistered and distained." (3) (evidence) The comforting and welcoming look of the main house is in sharp contrast to the door of the laboratory, which does not even have a bell to invite people in. The laboratory door is eerie and gothic highlighting the abnormal and mystical events that take place behind it. (analysis)

Incorporating Evidence

There are three standard ways to incorporate evidence into your paper: paraphrasing, summarizing, and quoting.

Paraphrasing and Summarizing

Paraphrasing is communicating the ideas of a source in your own words. Summarizing is communicating the essential or distilled argument of a source in your own words, without changing the meaning or intent of the original source. Paraphrasing and summarizing allows you to interrogate, criticize, analyze, or build on someone else's argument.

When paraphrasing or summarizing, you must make it absolutely clear that the ideas being presented are not your own, even if the words you are using to communicate them are yours. For example, if you are writing a philosophy paper that asks you to argue for an effective form of governance, you might choose to summarize Rousseau's ideas of participatory democracy and Hobbes' ideas on absolute monarchy; you could use phrases like 'Hobbes argues…' or 'Rousseau insists…' to highlight that what follows is not your original idea. You would then insert a citation at the end of the paraphrased or summarized evidence. You could then use this summary to compare the ideas, forming your own analysis.


Quotations are rarely used in scientific writing. Even in other disciplines, they should be used selectively; you want to make sure that the focus of your essay is on your own understanding of the topic and your own voice. However, quoting is useful when the source's exact words are special or distinctive, or when you want to preserve the full impact of the original source.

Depending on the assignment, you may also want to use quotations when the source itself is written by an authority on the topic. For example, if you are writing a paper on the history of multiculturalism in Canada, you may want to quote Pierre Trudeau, as the first Prime Minister to create an official policy on multiculturalism in Canada.

There are two types of quotations: short and long. Generally, shorter quotations are more effective. Shorter quotations enable you to maintain your own critical voice while using evidence to support your own analysis. When we make decisions about what to include in a shorter quotation, a central question must be asked: Does the choice of words matter? If the specific words used do add to your argument, then quote. However, if there is nothing remarkable about the words used, paraphrase or summarize the argument.

For example:

Personal narratives are important not only for one's own identity, but for the identity of a community even if that community is not physically housed anywhere (claim). Young argues these narratives are "a ritual process" that "ultimately [allows the homeless] to reclaim their lost sense of community." (338) (evidence)

Long quotations are, generally, only used in longer pieces of writing (at least 8-10 pages). They are useful when you would like to examine or refute another critic's work in detail. However, if possible, you should still tailor the quotation to your paper by using ellipses […] or dividing it into separate parts. It is also good practice to lead into the quote with a full sentence or two explaining to your reader why this quote is important and follow the quote with an explanation or analysis of it. For example, in a paper on the importance of personal narratives to identity, you might integrate a long quote as follows:

Personal narratives are important not only for one's own identity, but for the identity of a community even if that community is not physically housed anywhere (claim). Young argues this is especially important when a community has been discriminated against or is perceived as invisible in society (introduction of quote):

Stories bring people together. Speaking before congressional committees is a way of combating invisibility, a method of situating oneself, a means of overcoming liminality. Testifying may be a ritual process which offers the homeless the opportunity to reassert their humanity and ultimately to reclaim their lost sense of community (338). (evidence)

So to review what has been said so far, when you are wondering whether to quote, ask yourself: Why did I choose this particular quote? Why does this evidence matter to my argument? Why does the particular language of the quote matter?


It is important to remember that evidence does lend your claims credibility; without evidence, your claims will register only as opinion. It is also very important to remember that to use evidence effectively means to incorporate it well and to analyse it in a way that makes its connection to your argument clear and logical.

Citing your Evidence

Finally, after integrating your evidence into your paper, it is very important that you properly cite your evidence. Each discipline has their preferred style (MLA, APA, Chicago, etc.); if you are unclear what citation style to use, ask your professor or teaching assistant for direction.

Key words: evidence, supported/unsupported fact, example, statistics, quotations

For every claim you make in your writing, you will be required to prove your point. Your opinions and generalisations will need factual detail (evidence) to support them. Those supporting details may come from a number of different types of sources.

Please note that the APA referencing style is used in this workshop.

About placing evidence in your essay

In a standard essay, you can follow these general rules (i.e. rules may vary) about where you should put your evidence:

Click on each link for a description.

Introduction paragraphs
(about 5% of essay word count). INTRODUCTION PARAGRAPHS have a special function. Unless you are referencing a definition or an important introductory fact, avoid using references in your introductions.
Body paragraphs
(about 90% of essay word count). BODY PARAGRAPHS carry your evidence (e.g. explanations, arguments, examples). You will need to use a number of references in almost every paragraph to support your claims.
Conclusion paragraphs
(about 5% of essay word count). CONCLUSION PARAGRAPHS have a special function. Unless you intend to finish your conclusion with a final dramatic statement from a powerful source, avoid using references in your conclusions.

Supported facts and unsupported facts

Statements in academic writing need to be supported by factual details. When you are editing your writing, you will need to check that you have supported your claims with adequate evidence. For example:

Facts not supported with evidenceFacts supported with evidence
Many students seek assistance with their writing skills at university.Wonderland University (2016, p. 36) reports that during the academic year, lecturers recommended that 396 internal and 267 external students should seek assistance with their writing.
Writing academic paragraphs is the most important skill in academic writing.The Australian Association of Essay Writing (2012, p. 129) claims that their research in five universities shows that students are required to write academic paragraphs in 90% of their assessment tasks.
Exercise 1: Recognising supported and unsupported facts

Check the following sentence to see if you can recognise unsupported and supported facts:


The learning and teaching report showed that incorrect punctuation caused the most problems for students in conveying meaning in their essay writing (Department of Student Services, 2013, p. 23).

Fact supported with evidence


Unsupported fact



To convey meaning, students must punctuate their work correctly.

Fact supported with evidence


Types of supporting details

There are a number of ways you can support your claims in writing by using information/evidence from the work of (significant) writers and researchers. The following are three of the most common techniques:

  1. Quotations (e.g. direct quotes, paraphrases, summaries)
  2. Examples (e.g. illustrations of your points)
  3. Statistics (e.g. facts, figures, diagrams)
Exercise 2: Recognising types of supporting detail

Check the following sentence to see if you can identify quotations, examples and statistics:


Many student writers have difficulty with some aspects of punctuation. For example, researchers (George et al., 2016; Jones & Brown, 2013; Smith, 2012) find that many students misuse commas, mix up colons and semicolons and use capital letters incorrectly.


In its research project, the Literacy Foundation (2014, p. 167) argues that “common punctuation errors cause problems with meaning-making in student writing”.


The Literacy Reference Group (2017, para. 10) finds that more than 60% of the students who were assessed on their literacy scale made errors in their punctuation.

Using supporting and opposing ideas

When you have sorted out the position you will take in your essay, you will write a number of paragraphs to provide support for your stance. It is also equally valuable to find information that does not support your stance and argue against those opposite points of view. Statements that you use to do this can follow a simple pattern:

Writing support statements
  1. write support statement (sentence)
  2. write the reasons /evidence to support what you say (a number of sentences). Put your most important reasons first.

Read a 'supporting' argument

Supporting Argument

A number of researchers have noted that assignment tasks help students to learn the language of their subject (your statement). For instance, Smith and Jones (2014, p. 27) find that students who do assignments demonstrate a better use of the terminology of their subject when they write in their exams than students who do only exam assessment (evidence to support your statement).


Writing about the opposing ideas

  1. write a statement with the idea you disagree with (the opposing idea)
  2. write the reasons/evidence you have showing how your position is better (a number of sentences). Put your most important reasons first.

Read an 'opposing' argument

Opposing Argument

Some educators argue that assignments are time consuming to mark (your opposing statement). However, evidence from student feedback surveys finds that students value this feedback more than any other learning experience in their courses (Jackson & Peters, 2015) (counter evidence to support your opposing position).


Don’t do this!

  • Don’t put information in your essay that comes from the recesses of your mind without finding an authority to support your statements
  • Don’t use authorities that have no academic credibility (e.g. a popular magazine)
  • Don’t use your lecture notes (even with appropriate referencing) as the sole authority in your assignments

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