The graph in s.19 from the blog (which, again, you could have provided direct links) is manipulated in that it shows that 5 hours of sleep does indeed receive fewer injuries. However, looking at the study[1] and its actual graph though, Guzey is misrepresenting things quite a bit via omission. Here's what the study itself notes is their sample size:

> Of the 112 athletes studied, 64 athletes (57%) sustained a total of 205 injuries; 48 athletes (43%) were not injured. Of those who were injured, 42 athletes sustained >1 injury (38%). Table 1 includes a summary of the injuries by anatomic location.

And then:

> Sixty-five percent of athletes (56/86) who reported sleeping <8 hours per night were injured, compared with 31% of athletes (8/26) who reported sleeping ≥8 hours per night. Figure 1 shows the likelihood of injury over the 21-month period of reporting, based on hours of sleep per night.

And then the graph is provided which shows the likelihood of injury very strongly correlates to lack of sleep. With a sample size of 86, that 15% difference in the <5hrs group is basically 1 person. We don't know because we don't have the study's raw data that I can find (quickly, at any rate) but 3/5 people reporting < 5 hrs of sleep seems plausible, given that the < 5 hrs group is exactly 60% and given the other percentages for other groups present on the graph.

You can choose to believe dropping the < 5 hrs group is malicious manipulation I suppose but we're probably talking about a sample size of 5/112 for that particular data point. Would it have been better to show the full chart with the raw numbers of participants? Absolutely.

Ironically, Guzey then goes on to indicate the following:

> As an aside, that 9 hours of sleep column is based on exactly 1 child being injured out of 6 children who reported sleeping for 9 hours.

Whenever I see someone being this disingenuous (mentioning the detailed numbers when advantageous, leaving it out when disadvantageous) it makes me question their motives.

Absent knowing the real raw data, I have to consider that Walker's omission on the graph is still in line with the findings of the referenced study:

> In conclusion, lack of sleep and increasing grade in school appear to be associated with increased injury risk in an adolescent athletic population. Encouraging young athletes to get optimal amounts of sleep may help protect them against athletic injuries

Guzey's omission seeks to undermine this point. Perhaps criticism should be levelled at the study itself if that's the goal. Certainly sample size is probably an important factor, or other limitations identified by the study's authors, such as:

> A limitation of this study was that it was conducted at a single academically demanding, urban, private, combined middle school/high school, and the findings may not be generalizable to other populations in different geographic, socioeconomic, and educational settings. Further, the data are based on the self-reported survey responses of adolescents. Another possible limitation is that this study examines the adolescents’ reported chronic sleep deprivation. Acute sleep deprivation, such as getting minimal sleep on a more limited basis, may also put the athlete at increased risk of injury but would not have been captured by this survey as the average amount of sleep might be sufficient. In addition, the athletes were not asked about their dietary intake or specific medications, which may have an effect on their sleep or injury risk. We also did not account for napping in this population as a source of additional sleep. Several authors have shown that daytime napping can improve performance of both athletic and cognitive tasks.

Neither kind of omission are good approaches to presenting science and IMO raw numbers should be as available as possible for all of this kind of data.

[1]: M. D. Milewski et al. “Chronic lack of sleep is associated with increased sports injuries in adolescent athletes, Journal of Paediatric Orthopaedics 34, no. 2 (2014): 129-33. at: https://journals.lww.com/pedorthopaedics/Fulltext/2014/03000...