The Sleep and Grades Article
A student is researching whether later school start times improve academic performance. She finds four sources. Source A is a blog post by a parent arguing that teenagers are lazy, citing no data. Source B is a news article summarizing a peer-reviewed study of 9,000 students in eight districts, but the article does not link to the original. Source C is the original peer-reviewed study itself, published in a sleep research journal, with methods and limitations sections. Source D is a district newsletter reporting that one school moved its start time and "saw improvement," with no numbers. The student has one week and needs to build a defensible evidence base. She is tempted to cite Source A because it is easy to read and matches her own opinion.
1. Rank the four sources by evidentiary strength for this question and justify the ranking using specific criteria.
Read the worked answer
Strongest to weakest: C, B, D, A. Source C is the original peer-reviewed study: it has a stated sample (9,000 students), a described method, and an explicit limitations section, which lets a reader judge whether the conclusions follow from the data. Source B is a secondary summary of that same study; it is useful for orientation and for checking whether the student's reading of C matches an independent summary, but it omits the original's methods and cannot be verified without C. Source D reports an outcome with no numbers, no comparison group, and no method, so it is essentially an anecdote dressed as a finding - it cannot distinguish a real effect from coincidence or from other simultaneous changes. Source A cites no data and argues from characterization ("lazy"), so it offers no evidence at all. The ranking rests on verifiability, methodological transparency, and independence from the conclusion, not on readability or agreement with prior belief.
2. The student wants to cite Source A because it supports her existing view. What reasoning error is this, and how should she handle sources that conflict with her position?
Read the worked answer
This is confirmation bias: seeking or favoring evidence that supports a pre-existing belief while discounting contrary evidence. A related error is treating ease of reading as a proxy for credibility. The fix is procedural, not just attitudinal. First, she should pre-commit to criteria (peer review, sample size, method transparency, recency, relevance) before judging any source, so the standard does not shift based on whether she likes the conclusion. Second, she should actively search for the strongest counter-evidence - for example, studies finding no effect of start times - and represent it fairly in her write-up. Third, she should note where Source A's claim could be tested and whether any credible source supports it. If after this process Source A still contributes something (perhaps illustrating a common public perception), she may mention it as an example of a viewpoint, clearly labeled as unsupported by data, rather than as evidence for her claim.
3. Source B summarizes Source C but the student cannot access C's full text. What should she do, and what should she avoid claiming?
Read the worked answer
She should treat Source B as a pointer, not a substitute. Practical steps: look for the study's abstract and any open-access version; check whether the news article names the authors, journal, and year so the original can be located; and look for other independent summaries to cross-check B's characterization. She should avoid claiming that she has verified the study's methods or results if she has only read a summary - that overstates her evidence. She should also avoid citing specific statistics from B as if they came from C unless B quotes them directly and she can confirm them. In her write-up she can say: "A news summary of a peer-reviewed study of 9,000 students reports improvement; the original was not available for full review," which is honest about the limits of what she checked. Transparency about source access is part of credible sourcing.