Combatting Anti-Vaccine Misinformation
1) How do I figure out what is true, and what is false, about vaccines?Open or CloseIt is a sad but undeniable fact that there is a lot of misinformation, and in some cases downright lies, circulating about vaccines. This is especially true for the MMR vaccine, but the pernicious effects of the “anti-vaxxers” movement have expanded to the HPV vaccine as well. A recent outbreak of measles in the US has affected more than 100 individuals in 21 states and the District of Columbia. This follows on the heels of outbreaks in 2017, 2016, 2015, etc., including a record number of 667 cases in 2014. How bad is this anti-vaccine mania? Wealthy neighborhoods in Santa Monica and Beverly Hills now have vaccination rates that are similar to those seen in Chad and South Sudan. At some schools more than 60 percent of the kids have filed “personal belief exemptions” that allow them to avoid vaccination.
In my answers to the questions below I’ve listed a number of books and websites that I would recommend so you can learn the facts about how vaccines work, and why the anti-vaccine movement ignores the science.
In the case of HPV, the CDC has assembled a full page of educational and other resources. You can look at similar pages for other vaccines, including measles, shingles, polio, tetanus, and many others. The CDC also has developed an excellent full page graphic outlining all of the steps a vaccine must go through before it can be sold, as well as the systems in place to monitor the vaccine’s safety record after it enters the market.
Note: Some of the information on the internet, either in support of or against vaccines, is actually posted by Russian Trolls are spreading misinformation about vaccines on the internet. Their goal is simply to foment discord. Think critically about any vaccine information that you come across, either positive or negative.
You can also look at the website Media Bias/Fact Check, which maintains a list of conspiracy/pseudoscience websites that you do NOT want to be getting your information from, along with a list of science based websites that are factually based.
If you’re interested in the link between the anti-vaccine movement and conspiracy theories, take a look at this excellent video from Dr. David Robert Grimes, who studies these issues. A clear explanation as to what leads to vaccine hesitancy, and why it’s not worth the time to try to convince anti-vaccine conspiracy believers that they are wrong.
A good place to start is the History of Vaccine Safety page on the website of the Centers for Disease Control (CDC). You can also learn about the National Childhood Vaccine Injury Act of 1986 in this same place, and why it was necessary to develop this legislation.
A FREE newly published review paper in Feb. 2019 is an excellent source for getting a handle for what is, and what is not true, in vaccine safety.
DeStefano et al Principal Controversies in Vaccine Safety in the United States. Clinical Infectious Diseases, ciz135, https://doi.org/10.1093/cid/ciz135
If you want to learn about the various themes circulating in anti-vaccine rhetoric online, I recommend this excellent paper by Hoffman et al https://doi.org/10.1016/j.vaccine.2019.03.003 It’s not all about autism: The emerging landscape of anti-vaccination sentiment on Facebook. (FREE download).
Vaxopedia has a compilation of 100 myths about vaccines. Yes, there really are at least that many circulating.
Check out this blog post which refutes 72 anti-vaxx arguments against vaccines.
You can also take a look at Assessing the State of Vaccine Confidence in the United States: Recommendations from the National Vaccine Advisory Committee
One of the topics that comes up frequently are the data stored in the VAERS (Vaccine Adverse Event Reporting System) database. The CDC has a very clear explanation about how this system works, and the limitations on the data within it. In short, info in the VAERS database does NOT represent cause and effect relationships. As the website says, “When evaluating data from VAERS, it is important to note that for any reported event, no cause-and-effect relationship has been established. Reports of all possible associations between vaccines and adverse events (possible side effects) are filed in VAERS. Therefore, VAERS collects data on any adverse event following vaccination, be it coincidental or truly caused by a vaccine. The report of an adverse event to VAERS is not documentation that a vaccine caused the event.” You can also take a look at the VAERS homepage, which again has a wealth of information including info on how to file an adverse event report.
Check out this well written story about Why the Government Pays Billions to People Who Claim Injury by Vaccines to get a better understanding of the Vaccine Injury Compensation Program, the National Childhood Vaccine Injury Act of 1986 (also known as the Vaccine Act), and the Vaccine Injury Table, which details the many different illnesses, disabilities, and injuries that are presumed to be caused by a vaccine if no other cause is found.
2) Are there any good books to read about why people who oppose vaccinations are seriously misinformed?Open or CloseIndeed there are. Take a look at:
The Panic Virus: The True Story Behind the Vaccine-Autism Controversy by Seth Mnookin (2011). A detailed expose about the Andrew Wakefield/vaccines cause autism scandal in Great Britain. This book won the National Association of Science Writers Science in Society Book Award, and was named one of The Wall Street Journal's Top 5 Health and Medicine books of the year.
On a more personal level, I’d also recommend Vaccines Did Not Cause Rachel’s Autism: My Journey as a Vaccine Scientist, Pediatrician, and Autism Dad (inspired by his daughter) by Dr. Peter Hotez. As the title indicates Dr. Hotez is a pediatrician, a highly respected vaccine researcher, and the parent of a daughter with severe autism who suffers from intellectual difficulties. He explains the science regarding why vaccines don’t cause autism, what is thought to cause autism, and how he works to combat the voices of anti-vaccination groups.
Do Vaccines Cause That?! A Guide for Evaluating Vaccine Safety Concerns by Martin G. Myers, MD, and Diego Pineda (2008). Does exactly what the title says it does.
There are also four other books I can recommend to learn more about the anti-vaccine movement. Both were written or co-authored by Dr. Paul Offit, a very well known vaccine expert who led a successful effort to develop a vaccine against rotavirus (which can cause fatal diarrhea). This vaccine is saving the lives of hundreds of children across the world every day.
Deadly Choices: How the Anti-Vaccine Movement Threatens Us All (2012) - I highly recommend this one. It covers similar territory to the Panic Virus, but Mnookin’s book is written by a journalist, Offit’s book is written by a physician-researcher who has lived and breathed this subject for years. He is largely responsible for the development of the rotavirus vaccine, which saves the lives of hundreds of children somewhere in the world every day.
Bad Advice: Or Why Celebrities, Politicians, and Activists Aren’t Your Best Source of Health Information (2018) or to put it another way, why the internet isn’t the best place to get your health care information. In this book Dr. Offit explains why you shouldn’t be getting your healthcare advice from Gwyneth Paltrow and her ilk. He also explains why he seldom gets in front of the public to argue with anti-vaxxers. The book is a fast read and basically covers two ideas. About half of the book explains why much of the information available from people with no training in medicine or science is at best mostly worthless and at worst sometimes dangerous. He also gives some very good advice for scientists who are planning on engaging with the press to challenge this bad information. Much of this advice is based on his (few) professional career missteps and is meant to guide you to best handle (and hopefully avoid) lawsuits, death threats, biased debate moderators, and ineffective arguments from those you engage with.
Vaccines and Your Child: Separating Fact from Fiction by Paul Offit and Charlotte A. Moser (2011). This book is focused on allaying parent’s fears about vaccines.
Autism's False Prophets: Bad Science, Risky Medicine, and the Search for a Cure by Paul Moffit (2008). This book is an expose of all that went wrong when autism in children was unfairly linked to the MMR vaccine by a British doctor who’s research has been debunked.
In putting together this website, I’ve tried to always include links to authoritative sources for the data I’m quoting. However, I suggest you always consult your doctor or medical provider for the best and most recent information. Science and medicine change constantly as new discoveries are made, and I can’t guarantee that everything on even my website is up to date.
3) I want to learn why people who oppose the HPV vaccine (and others) are wrong. What are the facts?Open or CloseI’d start with this article, which is freely available online:
Robert A. Bednarczyk Addressing HPV vaccine myths: practical information for healthcare providers. Human Vaccines and Immunotherapeutics. (2019) https://doi.org/10.1080/21645515.2019.1565267
You might want to take a look at Answering human papillomavirus vaccine concerns; a matter of science and time by David Hawkes, Candice E Lea, and Matthew J Berryman from Infectious Agents and Cancer 2013, 8:22 (free, open access).
I also came across an interesting website that has answers to questions that are frequently asked about HPV and cancer, but with two completely different answers to each question. One set of answers is taken from a conservative website (Conservapedia HPV vaccine FAQ), and the second answer to each question is a set of reality based responses based on the science. An interesting look at just how differently this subject is viewed, and how little science based information is available on the Conservapedia site.
In addition to reading the books I listed above, there are a number of resources that you can turn to. One that I recommend is the Respectful Insolence website. The author of this website, Dr. David Gorski, invests a lot of time debunking studies that purport to show damage caused by vaccines, including the HPV vaccine. As of August 2018, he’s written 148 different blog posts exposing the problems with these anti-vaccine studies. Among these posts are ones specifically focused on HPV. Here’s just one example you can look at: A dumpster fire of a study about HPV vaccination and female fertility, courtesy of Gayle Delong
Some of you might enjoy comedians Penn and Teller’s humorous explanation for why all modern vaccines have great value. There’s also a good music video with an HPV-tinted version of the song More Than Words, originally made popular by Extreme. This version is from ZDogg, MD the online identity of internist Zubin Damania, MD. It’s medically accurate, as you would expect from a doctor. There’s also a humorous video HPV Barbie, which unfortunately gets the facts wrong. It might get people talking about HPV, but it’s a good example of why you need to keep in mind that everything you hear about vaccines online is not true. I don’t think Mattel is going to like it, especially since they cite incorrect facts about the HPV vaccine.
Commentator and comedian John Oliver also had some good insights to share about the value of vaccines in this video from Last Week Tonight.
4) So you’re saying that all vaccines are completely safe?Open or CloseActually, I’m not. Vaccines are truly one of mankind’s greatest inventions, and they have saved hundred of millions of lives over the past few centuries. Vaccines, like many things, are not, and likely will never be, completely safe for every individual that receives them. With billions of doses having been given, it’s not at all surprising that there will be rare but serious side effects (see the list here from the CDC). However, you’re more likely to be attacked by a shark or hit by lightning than to suffer one of these. Good scientists acknowledge this fact, and will point out the issues involved. An opinion piece in the NY Times suggested that some scientists have gone overboard in defending vaccines against the anti-vaxxer crowd, hesitating to acknowledge that some vaccines do indeed cause rare problems for some people who get them. Vaccine expert Dr. Paul Offit responded by pointing out that these infrequent vaccine injuries have not been hidden. They’ve been published, often and widely, though the quality of these reports varies greatly. Good scientists know that bad science does get published, but as it tends not to be replicable, most of it eventually falls by the wayside.
5) Since the HPV vaccine prevents numerous cancers, why is it so hard to have people act on that info?Open or CloseIt’s a complicated issue, but I can refer you to the following articles that discuss this:
Read about the many issues in getting people to want to be vaccinated in
Assessing the State of Vaccine Confidence in the United States: Recommendations from the
National Vaccine Advisory Committee. Approved by the National Vaccine Advisory Committee on June 10, 2015
What makes some parents fall for anti-vaccine messaging: Public health officials may not be hitting on the right morals in their quest to get all children vaccinated.
Here's The One Thing Scientists Have Found Will Change Anti-Vaxxers Minds: Logic is futile.
The 'Attitude Roots' Underlying Antivaccination Beliefs
Inadvisable anti-vaccination sentiment: Human Papilloma Virus immunisation falsely under the microscope, Head ed all npj Vaccines volume 2, Article number: 6 (2017)
A Hundred Thousand Wombs by Riko Muranaka, a personal look at how rumors about the safety of HPV vaccine in Japan caused vaccination rates to plunge. The author won an award for exposing these rumors as false. The story is also covered in Why Japan’s HPV vaccine rates dropped from 70% to near zero, and how one doctor is fighting back.
6) Is there a good site on the internet to find out if rumors about vaccines are true or false?Open or CloseYes. The best site I’ve found on the internet for checking out ALL rumors (not just those about vaccines) is SNOPES.com. It’s very reliable, and you can read about the methodology that they use here.
Here’s an example of their debunking of a rumor about the HPV vaccine:
FALSE: Pediatricians’ Association Admits HPV Vaccine-Cancer Link: A misleading article claimed that an association of pediatricians had "admitted" a link between the human papillomavirus vaccine Gardasil and ovarian "failure" or cancer.
7) Are there any good TED talk videos online about vaccines, vaccine safety, and fear of vaccines?Open or CloseThere are quite a few of these. The descriptions below are all taken directly from the online details about the TED talks on You Tube.
Seth Berkley: The troubling reason why vaccines are made too late, if they’re made at all. 7:17 in length (from 2015).
“It seems like we wait for a disastrous disease outbreak before we get serious about making a vaccine for it. Seth Berkley lays out the market realities and unbalanced risks behind why we aren't making vaccines for the world's biggest diseases.”
Tara Haelle: Why Parents Fear Vaccines. 12:15 in length (from 2016)
“Tara Haelle will focus on vaccine hesitancy and vaccine refusal. This is a global health threat that lurks unnoticed until it erupts into unpredictable disease outbreaks that are difficult to contain. She explains what underlies the fear and hesitancy that many people have toward vaccines, why it's not as irrational as some believe, and what's necessary to address it.”
Danielle Stringer: Why I Changed My Mind On Vaccinations. 16:28 in length (from 2017)
“”Vaccines are BAD! Wait! Vaccines are GOOD!" - Pediatric Nurse Practitioner, Danielle Stringer, shares her experience and ideas that caused her to leave her vaccine-hesitancy behind and advocate for immunizations.”
Dr. Lindsay Levkoff Diamond: Vaccination: A Story of Risk & Community. 13:09 in length (from 2015)
“Herd immunity works for vaccinations as it does Facebook share fact checking. Dr. Lindsay Diamond discusses the risk about the vaccination choice that parents face. What is risk and what does community do to our choices?”
Catharine Young: Tracking the journey of vaccines. 4:22 in length (from 2017)
“Why are so many vaccines manufactured never getting to the public to save lives? Neuroscientist and TED Fellow Catherine Young uncovers the answer through her mobile app that tracks the journey of vaccines by monitoring drivers. The data she gathers will help uncover weak points in the supply chain, and allow for specific solutions.”
8) What general talking points to you recommend when trying to convince people to vaccinate their kids?Open or CloseLet me point you to two really excellent resources:
The WHO has published Best Practice Guidance: How to Respond to Vocal Vaccine Deniers in Public. This is freely available online. Here’s what’s covered:
Chapter 1: Introduction
1.1. What situation does this document address?
1.2. The term vaccine denier
1.3. Who are vocal vaccine deniers?
Chapter 2: The target audience
2.1. Understanding the target audience
Chapter 3: The speaker
3.1. Who should be the spokesperson?
3.1.1. Being a good speaker
3.1.2. Being a good listener
3.2. Do’s and don’ts of communication
Chapter 4: The argument
4.1. Response to vocal vaccine denier
Chapter 5: Unfavorable interview conditions
Chapter 6: Embracing the opponent
Chapter 7: Religious beliefs
7.1. How to respond to religious concerns?
Chapter 8: How to behave in a passionate discussion
Chapter 9: Participating – or not
Chapter 10: Fake experts
Chapter 11: What now?
Annex 1: HURIER model of listening instruction
Here are a number of talking points, borrowed from vaccine expert Dr. Peter Hotez, from his book Vaccines Did Not Cause Rachel’s Autism: My Journey as a Vaccine Scientist, Pediatrician, and Autism Dad (inspired by his daughter):
1) Childhood vaccines save lives
2) Childhood vaccines do NOT cause autism, plain and simple
3) Autism is caused by something other than vaccines
4) There is an abundance of deliberately misleading information about vaccines on the Internet
Dr. Hotez has also highlighted a number of myths that circulate widely
1) Mandatory vaccination is part of some type of conspiracy
2) These infectious diseases are gone, and therefore we don’t need vaccines
3) More children die in the US from vaccines compared to the diseases they prevent
4) Our body’s own “natural immunity” provides adequate protection from these infectious diseases
5) There’s a need to be concerned about vaccine ingredients
9) Got any resources for doctors and other medical professionals regarding how to get patients to accept the HPV vaccine?Open or CloseI think there are actually a large number of these. I’ll add to this list over time. Let’s start with:
The CDC has this helpful one page guide for talking to parents about the HPV vaccine. They also have this general guide for talking to parents about all vaccines.
Here’s advice about talking to vaccine-hesitant parents from the American Academy of Pediatrics.
The World Health Organization also has a resource for talking to parents about vaccines.
Here’s advice from the Canadian Pediatric Society in dealing with vaccine hesitant parents.
And a guide from vaccineresources.org, a handbook for healthcare workers and parents from PATH
ACIP (Advisory Committee on Immunization Practices) guidelines can be found on this page of the CDC website.
Vaccination resources from the WA state Dept. of Health can be found here.
Here’s a good article looking at approaches that work, and those that don’t, in convincing parents to vaccinate their kids. Bottom line: don’t ask about vaccination; simply be presumptive and tell parents it’s time for vaccination. If parents have concerns, acknowledge them, answer any questions they have, and tell them that in your professional judgement the risks are minor with vaccines, and the benefits greatly outweigh them.
HPV IQ - Immunization improvement, assessment, and feedback tools, along with communication training tools.
The CDC’s AFIX program - AFIX is a quality improvement program conducted by CDC’s immunization program awardees to support Vaccines for Children (VFC) providers in their jurisdiction. The goal of the AFIX program is to increase vaccination of children and adolescents with all Advisory Committee on Immunization Practices (ACIP)-recommended vaccines by reducing missed opportunities to vaccinate and improving immunization delivery practices at the provider level. The AFIX program consists of four components: Assessment, Feedback, Incentives, and eXchange.
10) Some anti-vaccine individuals and websites say that my religion doesn’t permit the use of certain vaccines, including the HPV vaccine. Is that true?Open or CloseIt’s not true. The real answer is that ALL of the major religions of the world are OK with ALL of the currently available vaccines, including the HPV vaccine. However, in some religious groups, some people have not been getting vaccinated due to social norms, not due to any prohibition by their religion. To learn more, check out this very comprehensive review of the subject that covers a wide range of religious groups, including all of the worlds major religions:
Grabenstein, J. What the World’s religions teach, applied to vaccines and immune globulins. Vaccine 31 (2013) 2011–2023. FREE download.
More info about how leaders from all religious groups endorse vaccines, and why creating newer vaccines to replace existing (and effective) vaccines can be seen in Religious Objections to the Measles Vaccine? Get the Shots, Faith Leaders Say
11) What are the specific claims about harms caused by the HPV vaccine, and who has debunked them?Open or CloseDispelling the Major HPV Vaccine Safety Myths
There’s a lot of misinformation on the Internet surrounding the HPV vaccine. I debated even covering this subject here, fearing that even mentioning any possible side effects would somehow cause people to believe them without checking out the data. For those of you who “like to do your own research”, you can start by looking at the reference sources I site below. There are a large number of studies that have been done, so I will focus on both the largest studies, as well as studies that compiled the results of previous studies.
Let me say at the outset that vaccines are NOT 100% safe. Any scientist or healthcare provider who makes such a claim is unbelievable. Drugs are also not 100% safe, and the same is true for all types of surgery. Nor are automobile airbags, bicycle safety helmets, or the foods we consume daily. Despite this fact, we use these things all the time because we know that the benefits of doing so greatly exceed the risks. The same is true for vaccines. They help keep us healthy, save lives, and prevent a great deal of disease-caused misery.
Let’s focus on the various HPV vaccines that have been used since 2006. What this vaccine was designed to do was to prevent cancer and, in the case of the two later Gardasil and Gardasil 9 vaccines, also prevent genital warts.
The HPV vaccine does NOT cause premature ovarian failure i.e. sterility
The HPV vaccine does NOT cause postural orthostatic tachycardia syndrome
The HPV vaccine does NOT cause complex regional pain or other neurological syndromes
The HPV vaccine does NOT cause demyelinating syndrome
The HPV vaccine does NOT cause venous thromboembolism
We know this because all of these have been looked at in vaccine safety studies.
Phillips, A. et al. Safety of Human Papillomavirus Vaccines: An Updated Review. Drug Safety April 2018, Volume 41, Issue 4, 329–346. This is a very complete review, but unfortunately, it’s behind a paywall.
The researchers compiled all of the data in a number of HPV vaccine studies published to date, including several different versions of the vaccine. They analyzed all of it, and here’s what they had to say, “We identified 109 studies, including 15 population-based studies in over 2.5 million vaccinated individuals across six countries. All vaccines demonstrated an acceptable safety profile; injection-site reactions were slightly more common for 9vHPV vaccine (Gardasil 9) than for 4vHPV vaccine (Gardasil). There was no consistent evidence of an increased risk of any adverse events of special interest.”
In a separate study, Scandinavian researchers looked for evidence of HPV vaccine side effects in nearly one million girls age 10-17. About 300,000 girls had gotten the vaccine; the remainder served as controls. Potential vaccine side effects had to be noted within 180 days of receiving the immunization. Here are their conclusions, “This large cohort study found no evidence supporting associations between exposure to qHPV vaccine [the original Gardasil vaccine] and autoimmune, neurological, and venous thromboembolic adverse events. Although associations for three autoimmune events were initially observed, on further assessment these were weak and not temporally related to vaccine exposure. Furthermore, the findings need to be interpreted considering the multiple outcomes assessed.”
Now their analysis did find some weak signals suggesting a possible involvement of the vaccine in three autoimmune diseases: Raynaud’s disease; type 1 diabetes, and Behcet’s syndrome. As a result, they did a more in-depth analysis of the data for these specific illnesses, and here is their conclusion: “While the study expands on the current safety information of the qHPV vaccine [Gardasil] by systematically assessing a range of serious adverse outcomes, the results need to be interpreted cautiously considering the large number of statistical tests performed; as well as the chance of false positive findings, true associations may have been missed. Although significantly increased rate ratios were initially observed for three outcomes, further assessment showed no consistent evidence for a plausible association; firstly, these risk signals were relatively weak, as assessed by pre-specified criteria, and, secondly, no temporal relation between vaccine exposure and outcome was evident. Thus, this study identified no safety signals with respect to autoimmune, neurological, and venous thromboembolic events after the qHPV vaccine had been administered.”
Arnheim-Dahlstrom, L. et al. Autoimmune, neurological, and venous thromboembolic adverse events after immunisation of adolescent girls with quadrivalent human papillomavirus vaccine in Denmark and Sweden: cohort study. BMJ 2013;347:f5906 doi: 10.1136/bmj.f5906 (Published 9 October 2013). This is a FREE open access article.
The Canadians have also looked for serious adverse events associated with the HPV vaccine. Here are the results of their study, “Over the period 2006-2014 195,270 females received 528,913 doses of HPV vaccine. Of those receiving at least one dose, 192 reported one or more AEFI events (198 AEFI events), i.e., 37.4/100,000 doses administered (95% CI 32.5-43.0). None were consistent with venous thromboembolism (VTE). Of the women who received HPV vaccine 958 were hospitalized and 19,351 had an ED visit within 42 days of immunization. Four women who had an ED visit and hospitalization event were diagnosed with VTE. Three of these had other diagnoses known to be associated with VTE; the fourth woman had VTE among ED diagnoses but not among those for the hospitalization.”
Liu, X.C. et al. Adverse events following HPV vaccination, Alberta 2006–2014. Vaccine, 34, 15, 2016, Pages 1800-1805. This is a FREE open access article.
In the spirit of overkill, I’ll give you a few more examples.
Researchers from Kaiser Permanente in CA looked for potential autoimmune side effects of the HPV vaccine in nearly 190,000 girls. The authors concluded, “Overall, 1014 potential new-onset cases were electronically identified; 719 were eligible for case review; 31–40%were confirmed as new onset. Of these, no cluster of disease onset in relation to vaccination timing, dose sequence or age was found for any auto-immune condition.”
Chao, C. et al. Surveillance of autoimmune conditions following routine use of quadrivalent human papillomavirus vaccine. J. Internal Med. 271, #2, 193-203 (2012). This is a FREE open access article.
Canadian researchers looked at adverse events in 195,000 young women following the HPV vaccine. Their overall conclusion: rates of adverse events were low, and consistent with those seen in other studies.
Liu, X. Adverse events following HPV vaccination, Alberta 2006–2014. Vaccine 34 (2016) 1800–1805 http://dx.doi.org/10.1016/j.vaccine.2016.02.040 This is a FREE open access article.
The HPV vaccine also does not lead to death in young women. For this, I’ll refer you back to the above articles, but also to this debunking piece on Snopes.com.
So the data is indeed available. The HPV vaccine is pretty darn safe.
12) How can I tell the difference between good and bad science papers?Open or CloseThese are not alway easy to distinguish if you’re not a trained scientist, but it is doable. Brooke Fotheringham, mom and photographer with a passion for science communication and public health has written a terrific guide Recognizing good and bad science in vaccine research for separating the reliable scientific wheat from the disposable chaff. One of the techniques that she uses to do this is the Smell Test that was developed by author John McManus:
S stands for Source. Who is providing the information?
M is for Motivation. Why are they telling me this?
E represents Evidence. What evidence is provided for generalizations?
L is for Logic. Do the facts logically compel the conclusions?
L is for Left out. What’s missing that might change our interpretation of the information?