The paper's own discussion section explicitly acknowledges potential weaknesses:
This study has several important limitations. First, the quasi-experimental design of our
study limits our ability to draw any causal conclusions between the release of 13 Reasons Why
and increased suicide rates in young people in the U.S. Nevertheless, the time series and
forecasting approaches employed in this study allow us to make credible inferences about this
association. The initial increase in youth suicide rates in the month immediately following the
series release is concordant with a prior report showing a spike in Internet searches about
suicide in the month following release,46 and a small single-hospital study showing an increase
in suicide attempt admissions after the series’ premiere. Second, we were unable to assess
whether the observed increase in youth suicide rates was attributable to the portrayal of suicide
in the series, a lack of adherence to media guidelines (e.g., failure to provide national suicide
prevention resources until later months), or other factors. The observation that the series was
first released on March 31, 2017 and suicide rates increased that month also raises questions
about effects of pre-release media promotion of the series premiere. Third, we did not examine
the impact of 13 Reasons Why on specific methods of suicide (e.g., suicide by cutting) due to
small cell sizes, which would result in unstable estimates. Fourth, there may have been other
events or unmeasured factors that occurred during the study period that might be associated
with increased suicide rates. Fifth, our study may have lacked sufficient statistical power to
detect a significant association in 10- to 17-year-old girls. Finally, as with most studies looking at
possible contagion, we have little understanding of “dose” or context, including who specifically
watched the series, when they watched, whether they binge-watched, if it was further discussed
in peer-groups, how secondary discussions may have influenced vulnerable individuals, and
whether the subsequent focus on suicide prevention may have actually mitigated some of the
pronounced contagion effects.
This study has several important limitations. First, the quasi-experimental design of our study limits our ability to draw any causal conclusions between the release of 13 Reasons Why and increased suicide rates in young people in the U.S. Nevertheless, the time series and forecasting approaches employed in this study allow us to make credible inferences about this association. The initial increase in youth suicide rates in the month immediately following the series release is concordant with a prior report showing a spike in Internet searches about suicide in the month following release,46 and a small single-hospital study showing an increase in suicide attempt admissions after the series’ premiere. Second, we were unable to assess whether the observed increase in youth suicide rates was attributable to the portrayal of suicide in the series, a lack of adherence to media guidelines (e.g., failure to provide national suicide prevention resources until later months), or other factors. The observation that the series was first released on March 31, 2017 and suicide rates increased that month also raises questions about effects of pre-release media promotion of the series premiere. Third, we did not examine the impact of 13 Reasons Why on specific methods of suicide (e.g., suicide by cutting) due to small cell sizes, which would result in unstable estimates. Fourth, there may have been other events or unmeasured factors that occurred during the study period that might be associated with increased suicide rates. Fifth, our study may have lacked sufficient statistical power to detect a significant association in 10- to 17-year-old girls. Finally, as with most studies looking at possible contagion, we have little understanding of “dose” or context, including who specifically watched the series, when they watched, whether they binge-watched, if it was further discussed in peer-groups, how secondary discussions may have influenced vulnerable individuals, and whether the subsequent focus on suicide prevention may have actually mitigated some of the pronounced contagion effects.