Collecting Evidence

Learning Objectives

  • Describe strategies for preliminary research (gathering evidence) on a topic

Gathering Helpful Evidence

Once you have a topic picked out and have asked questions to find out more, you want to work on the next stages of the writing process—prewriting and finding evidence.

Remember your friend’s story about the people falling into the fountain before class—how could you verify its accuracy? What if your friend had lied to you in the past about these types of stories? Is he trustworthy? You may want proof that it happened, so you’d turn to another classmate and ask if they had seen anything. From there, you could ask others, or inquire more about the people involved to see if you could track them down to find out the whole story. This would all be the “gathering evidence” stage of the writing process.

"The Writing Process": Topic, Prewrite, Evidence, Organize, Draft, Revise, Proofread.

Figure 1. Finding all of your sources before organizing and outlining your essay allows you to have all the information necessary to effectively complete those steps.

Some evidence will be more useful than others, and some sources will be more valuable than others. The actual participants involved and eyewitnesses (the primary sources) will have the most accurate information. People who heard things secondhand from someone else (the secondary sources), will be less helpful. Some people will have more information about what happened (sufficiency), and others may have been there at the scene but mostly remember something else that was happening at the time (lacking relatedness).

Finding Evidence

Let’s think back to our example of school start times. If you were to write a paper about school start times, what types of evidence would you use? And which ones would you throw out?

Depending on which angle you chose to take (based on your narrowing questions), the type of evidence you search more may vary. For instance, maybe your narrowing questions led you to focus on the sleep benefits of a later start time. Or maybe your narrowing questions lead you to focus on the mental health benefits of a later start time, or maybe even on the benefits of less traffic congestion in your city. Whichever angle you take, your defining questions will help you decide which claims you want to support in your essay. You want to look for evidence to support such claims.

Try It

Building off your questions about delaying school start times you will want to determine which questions will help support a claim that you would like to make about delayed school start times. For instance, would you like to focus on the sleep benefits or the mental health benefits or perhaps less morning traffic congestion? Your defining questions help you narrow down your topic and direct you towards what evidence you need to collect.

If you are looking for evidence on the mental health benefits of later start times, you could expect to look in scientific journals such as medical journals, psychology journals, and sociology journals. You’ll be looking for specific details about the importance of sleep, how it affects clear thinking, and if or how it reduces anxiety, depression, relationships, or other mental health concerns. Generic searches can give you good background information, and popular news articles may nicely summarize the basics of the issue, but when you are authoring your essay, you’ll want to include specfic evidence from more scholarly sources, such as peer-reviewed articles.

Try It

Let’s look at this together from a scientific article: (

“One clear consequence of short sleep in adolescents is increased sleepiness [[1][2][3][4][5][6],[7],[8]]. However, until relatively recently, the evidence for the cognitive impact of reduced sleep was less conclusive. In a review of experimental studies between 1981 and 2015, de Bruin et al. concluded that sleep restriction had only a small or no effect on cognition in adolescents [9]. Even when sleep was reduced to as little as five hours for four nights, Voderholzer et al. [10] did not observe impairment of attention, speed of processing, executive function, working memory, or long-term memory. While this was attributed to adolescents’ ability to preserve slow wave sleep[11] or to modulate task-related brain activation during partial sleep deprivation,[12] another possibility is that the cognitive tasks were not sensitive enough to detect the effects of partial sleep loss."

The passage written above comes from research by June C. Lo and Michael WL Chee, "Cognitive effects of multi-night adolescent sleep restriction: current data and future possibilities" from the Centre for Sleep and Cognition. If you just read that only paragraph, you may be inclined to think that their research indicates no correlation between lower performance and adolescent sleep, but that's not the case. This paragraph happens to be a part of their rebuttal, or the reasoning they give to the opposing viewpoint. They start with this before presenting more recent research that, "Adolescents are not immune to sleep loss-induced neurobehavioral impairment."

Let's read more from their research. This time, look for which specific sentences in the following paragraphs would best support your topic sentence of, "Lack of sleep for adolescents contributes to attention and memory problems in school."

The Psychomotor Vigilance Task (PVT), extensively used in studies involving partial and total sleep deprivation in adults, had only been used in a single non-adult study before 2016. In that study, more lapses in attention in the PVT were found after a night of five-hour time-in-bed (TIB) compared to a 10-hour TIB in 10-year-old girls.[13] Since 2016, several studies have corroborated the utility of examining vigilance decline in sleep-deprived teens. Campbell et al. found that children and young adolescents (age: 9.9–14 years) exhibited sustained attention deficits after four nights of 7.5-hour TIB [22••,23], despite the fact that slow wave sleep duration or activity were not compromised [24]. Lapses in attention were also observed in Short’s work involving older adolescents (age: >15 years) over five nights of 5-hour and 7.5-hour TIB[14],[15]].

In addition to vigilance (assessed with the PVT) and alertness (the Karolinska Sleepiness Scale), a series of experimental sleep studies we conducted on older adolescents also tracked working memory/executive functions (1-back and 3-back tasks), and speed of processing (the Symbol Digit Modalities Test and the Mental Arithmetic Test) over 10–15 days of sleep opportunity manipulation. Participants who had a 9-hour TIB throughout (Figure 1, black line), evidenced stable performance on the PVT and n-back tasks, and steadily improved on speed of processing tasks. In contrast, those restricted to 5-hour TIB over seven nights showed cumulative decrement in subjective alertness, sustained attention, and working memory/executive functions, in addition to no improvement in speed of processing.[16] This combination of findings was replicated in a subsequent study involving five nights of sleep restriction to 5-hour TIB.[17] Although two nights of nine-hour recovery sleep over a simulated weekend offered some respite, neurobehavioral deficits were compounded[18] upon a second exposure to 5-hour TIB nocturnal sleep restriction (Figure 1, red line). This compounding of behavioral effects over two successive cycles of sleep restriction was also observed with a milder, and perhaps more common, level of sleep restriction to 6.5-hour TIB[19] (Figure 1, green line).

Appropriate alternative text for this image can be found in the surrounding text.

Figure 1. Effects of sleep restriction and napping on vigilance in adolescents.

Writing Workshop: Analyzing Evidence

Let’s look at an article that addresses both health and performance effects of later high school start times and see how the authors use evidence to support their claims.

  1. The introductory paragraph (under the heading "Introduction") makes the following claim: "Despite the well-established natural shifts to later wake and sleep times that occur in adolescence, most schools retain early start times." How would you restate this claim in your own words? (Note: there are really two claims here-- try to address both!)Hint: Adolescents naturally …     But schools still ...[EXPLAIN THE CLAIM IN YOUR OWN WORDS... ]
  2. The next paragraph claims that "Adolescents need anywhere from 8 to 10 h of sleep per night for full health and academic performance depending on age and inter-individual differences, yet most get far less."[EXPLAIN THE CLAIM IN YOUR OWN WORDS... ]
  3. What sources are cited to back up the claim that adolescents need 8 to 10 hours of sleep?[LIST THE SOURCES CITED]
  4. What supporting claim is made about why adolescents get less than the necessary sleep?[EXPLAIN THE SUPPORTING CLAIM IN YOUR OWN WORDS... ]
  5. What source is cited to back up the claim about why adolescents get less sleep than they need?[BRIEFLY LIST THE SOURCE CITED]
  6. The authors conclude the paragraph with the claim that “Adolescent sleep restriction is clearly linked to early school starts as on non-school days adolescents have wake times two or more hours later (Roenneberg et al., 2007).” How does this sentence back up the claim that adolescents need 8-10 hours of sleep but get far less?[EXPLAIN THE SUPPORTING CLAIM IN YOUR OWN WORDS... ]
  7. In the final paragraph of the introduction (“The principle that”), the authors describe what their research study is about. What are they researching?


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