Hand holding a Social Media 3d Sphere

Social Media Index (SMi)

UPDATE (June 2023): This is now retired because Alexa Rank data is no longer available. The revised formula to rank open access blogs and podcasts is the Digital Impact Factor.

Academics have created indices to compare both scholars (h-index) and journals (Impact Factor) within a given field. The websites that contribute to the creation of Free Open Access Medical Education (FOAM) do not have a comparable parameter. This makes assessing the impact of each website challenging for both content producers and their supervisors. Additionally, learners may find it difficult to distinguish between reputable and unproven websites.

The Social Media Index (SMi) was developed to address these problems. It is a comparative index derived from three easily obtainable indicators including:

  1. Alexa Rank (of the website)
  2. Twitter Followers (of the website or most prominent editor – whichever is higher)
  3. Facebook Likes (of the website’s page)

For each website, these 3 indicators are normalized and added together to give a score ranging from 0 to 10. The details of the derivation and validation of the SMi are outlined in the Western Journal of Emergency Medicine1 while a study investigating the SMi’s correlation with quality has recently been published in Annals of Emergency Medicine.2 The 2021 SMi was calculated in the last week of December, 2020. It will be updated annually each December moving forward.

2021 Social Media Index (SMi) Rankings

The SMi ranking table demonstrates the annual rankings of each site since 2016.
Rebel EM975544
Emergency Medicine Cases1067665
Dr. Smith's ECG Blog656496
EM Docs2098757
First 10 EM3519191178
Don't Forget the Bubbles214215121510
EMS 12 Lead54491011
The Skeptic's Guide to EM231716141115
St. Emlyn's Blog151011151316
Core Ultrasound141218171417
The Resus RoomNRNRNRNRNR18
Ultrasound of the Week262223241919
Intensive Care Network12813101721
Emergency Medicine Updates181814161822
EM Basic221517182223
EM Ottawa BlogNR13796473924
Taming the SRU292335222425
Journal FeedNRNRNRNRNR27
EM Lit of Note171329252129
The Gurney RoomNRNRNRNRNR30
Resus ME282125262332
Broome Docs595460414534
Pharmacy JoeNR6242333635
Critical Care NorthamptonNRNRNRNRNR37
PEM Blog443637303238
EM Over EasyNRNR76623139
60 Second EM777049524040
Critical Care Practitioner433126213041
EM Curious395341404142
Western Sono624150374243
Clinical MonsterNR8557424445
PedEM Morsels494627323446
MD Aware949269534847
Rogue Medic484052434948
Thinking Critical Care11013097835249
Intensive BlogNR5759455051
The Short Coat8610287815852
Rolobot Rambles786573614653
Emergency Medicine PharmD1528680666554
Maryland CC Project12714170547556
EM in 51457572506257
Rollcage Medic1151251161067259
Trauma Professional's Blog606163676860
Emergency Medicine Ireland557778826361
EM Sim CasesNR10686736962
Sask Sonic126138120807363
ECG of the Week1201231291037864
Asystole: The Most Stable Rhythm1211141241117166
Emergency Phenomena806685777968

2021 Social Media Index (SMi) Values

The SMi values table demonstrates the Alexa, Facebook, and Twitter values collected for each site for the 2020 SMi.
WebsiteAlexaTwitterFacebookSocial Media Index
Rebel EM43116726500190876.0
Emergency Medicine Cases54644911800291745.8
Dr. Smith's ECG Blog105385227700694255.8
EM Docs3676541060077565.7
First 10 EM2866431130031745.7
RCEM Learning4482591740029675.5
Don't Forget the Bubbles76756511700111215.4
EMS 12 Lead2692513238001084515.3
Core EM6488751010035295.2
The Skeptic's Guide to EM152723419500109295.1
St. Emlyn's Blog14043472480045215.0
Core Ultrasound8682831670016475.0
The Resus Room16740791690067394.9
Ultrasound of the Week868283880313124.8
Intensive Care Network26624581530088004.7
Emergency Medicine Updates25717631470025074.4
EM Basic25693531530019404.4
EM Ottawa Blog1537161398618434.3
Taming the SRU1528048448315224.3
POCUS 10189132845793114.3
Journal Feed95479319717774.3
EM Lit of Note48969531400030014.1
The Gurney Room6431137662064.0
Resus ME8383307204009013.7
Broome Docs40910448588863.3
Pharmacy Joe837591927303.2
Critical Care Northampton934720923503.2
PEM Blog838330722957513.2
EM Over Easy838330721325973.1
60 Second EM838330715344962.9
Critical Care Practitioner1385623804602.9
EM Curious838330731871422.9
Western Sono838330724781662.9
NUEM Blog1561737433502.7
Clinical Monster1415798251302.6
PedEM Morsels2444346461002.5
MD Aware83833074620002.4
Rogue Medic7950870439872.4
Thinking Critical Care3790794566602.3
Intensive Blog4984358798602.3
The Short Coat83833071330002.1
Rolobot Rambles83833071290002.1
Emergency Medicine PharmD4065510276302.1
Maryland CC Project2757394101802.1
EM in 53737940200602.1
PEM Playbook6803834551602.0
Rollcage Medic8383307802102.0
Trauma Professional's Blog5728194346002.0
Emergency Medicine Ireland8383307662102.0
EM Sim Cases416227369201.8
Sask Sonic8383307157801.7
ECG of the Week630254160501.6
Asystole: The Most Stable Rhythm838330786101.5
Emergency Phenomena838330756401.4

SMI Calculator (Note: Not yet updated with 2021 data)


The detailed formula for the calculation of the SMi for an individual website is outlined below. Notably, each aspect must be related to the site on the index relative to the other sites highest/lowest Alexa, Twitter, and Facebook numbers:

Social Media index


We would appreciate your assistance in correcting any errors (Did we miss an Alexa Rank, Twitter Account, or Facebook page? Is our data inaccurate?). Feedback on the SMi can also be provided by tweeting @Brent_Thoma.


There have been numerous updates to the SMi over the years.

2013: Google deprecated the PageRank metric after our original publication1 and it was no longer be included in future versions of the SMi. Fortunately, our data in the 2013 WestJEM paper suggests that the Alexa score has a high correlation to PageRank. Because of this, we have elected to double the weight of the Alexa score in the SMi calculation to replace PageRank’s contribution. We have also modified the calculation of the Alexa component of the SMi. This change fixes the lowest ranking websites to the lowest value achieved by any indexed site. The effect of this change makes the score more consistent with the other components.

2018: The current formula was shown to correlate with quality.2

2019: Given the time demands of data collection, we transitioned to an annual data collection in December of each year that would be considered the subsequent year’s SMi for each site (e.g. data collected in December of 2019 make up the 2020 SMi).

2020: The inclusion criteria for each website has been clarified. Moving forward, sites already indexed will be retained for the subsequent year if they

  1. Focus on emergency medicine or critical care content
  2. Receive an Alexa score OR have posted content within the last calendar year
  3. Have either a Twitter page (editor- or site-specific) OR Facebook page (site-specific)

Sites will be included moving forward if they are nominated by anyone (tweet any sites meeting the criteria to @Brent_Thoma). To be included they will need to:

  1. Focus on emergency medicine or critical care content
  2. Receive an Alexa score
  3. Have either a Twitter page (editor- or site-specific) OR Facebook page (site-specific)


1. Thoma B, Sanders J, Lin M, Paterson Q, Steeg J, Chan T. The social media index: measuring the impact of emergency medicine and critical care websites. West J Emerg Med. 2015;16(2):242-249. [PubMed]
2. Thoma B, Chan T, Kapur P, et al. The Social Media Index as an Indicator of Quality for Emergency Medicine Blogs: A METRIQ Study. Ann Emerg Med. July 2018. [PubMed]
Brent Thoma, MD MA
ALiEM Associate Editor
Emergency Medicine Research Director at the University of Saskatchewan
Editor/Author at CanadiEM.org
Brent Thoma, MD MA