Thanks a lot, Sir. you made it so easy. It is so annoying that I have paid tuition fees for university and I still have to turn RUclips upside down to understand every concept better.
+Kahtan Thanks for the question. So Retrospective cohort studies can be a little confusing because, as you mentioned cohort studies are usually prospective. The important thing to remember is that a cohort study is always looking at a group (a cohort) who have all been exposed to an identifiable exposure and we're still wanting to know if over time, what outcomes might be associated with that exposure. In the case of a retrospective cohort study, the timeline that we follow is in the past (and we have some record of who was exposed to what and what the respective outcomes were).
Yes, this video summed up the main points well. Just started a basic course to wrap up a M.S. in Clinical Nutrition. So, rare outcome (disease) and exposure with rare results for the exposed groups in both case control and cohort studies. Thanks.
thank you so much for this video it helped me in my homework for the epidemiology class.. you provided the information in a very easy and interesting way!!
Hi Greg - In Kenneth J. Rothman's textbook; "Epidemiology: An Introduction (2nd edition)", Rothman talks about "Retrospective Cohort studies" (P.85). What is your take on that? He refers to a study conducted by Morrison et al. A study on data since 15th and 16th century in Florence. It is quite confusing (not what I needed on top of the heap of other epidemiology confusion) :P
Thanks for letting me know Marjorie Simpson (much appreciated). What are you students studying (and where)? Please let them know that they are welcome to get in touch with me if they have suggestions re future video content on this channel. I also host a weekly "live" global health news roundup every Wednesday at 2pm (EST) which that might be interested in. Find out more at www.twigh.org
Could you do a video on Attributable Risk, Absolute Risk Reduction (ARR), Number Needed to Treat (NNT), and Number Needed to Harm (NNH). These topics are all very similar and get confused. THANKS FOR YOUR VIDEOS!
Hi Greg. I am confused between retrospective cohort studies and case control studies. It seems like in both situations you look at people with a disease and people without a disease and then look back at exposure? Could you please explain the difference?
Dear Greg, thank you for this educational video. I have a quick question: how long would you recon a cohort study should last? If you write a thesis in about a year is it realistic? Or should it last over a number of years/decades?
Thanks for the question. The truth is that it's kinda like a piece of string... It's as long as it needs to be. That is to say, it depends on what's you're wanting to observe in your cohort. You may be looking at outcomes that take years to present (like cancer) or days (like the common cold). Hope that helps.
It's so simple and very informative, thank you so much. I subscribed your channel. Just one little favour, can you please speak a tiny bit slowly coz English is only my second tongue.
ok, so in case case control, we already have the outcome and we want to find out what exposures lead to the outcome. so this study does access temporality right
Can you give us an example for sake of deeper understanding when would you choose retrospective cohort and when would you choose case-control and under which circumstence would you choose one over other for a given problem?
Hi there - if you are looking at a rare condition - lets say hypothetically, people whose hair turned blue - you might want to consider a range of possible exposures that could have caused this. You'd look at diet, exposure to sunshine, genetics, the type of shampoo that they use etc. etc. (that would be a case control study). Start with the cases and look back at possible exposures. In a retrospective cohort (as in with any other cohort) your starting point is an exposure (not an outcome). You might for example be interested in what diseases have emerged following exposure to the radiation in Japan. There might be any number of outcomes. Your cohort is the group of people exposed. In this case however, the exposure is in the past (making it retrospective). Does that make sense?
Yes i finally think i do get it . If we have a known diesese but haven't figured out the causes yet, we will go with case-control, but if we have a known cause but we yet have to proove which diesese it can cause we will go with retrospective cohort.
You really broke the differences between a case control and cohort study down very simplistically. Thank you!
The explanation of the subject matter was spot-on. Thanks Dr. Greg!
Thanks a lot, Sir. you made it so easy. It is so annoying that I have paid tuition fees for university and I still have to turn RUclips upside down to understand every concept better.
Thank you for sharing your experience, and best of luck with your studies!
Concise and very helpful. I love the pictorial representation of the concepts!
Glad you liked it Jolene! Thanks for the feedback :)
one of the best tutorials on this subject brief yet concise!
Abdul Quadeer Mohammed thanks for the comment - much appreciated.
Thanks Dr Greg, your explanation is clear and easy to understand. Straight to the point
Thanks for the feedback Gemini! Much appreciated. Have a great day.
Muchas gracias por su excelente presentación. Saludos desde Ensenada, México.
You saved my life! I finally understand the exact diffrences between these two. Thank you!
Happy to help! You are so welcome!
hey! this is jennifer from 2020 and i just wanna say thank you for this video. great explanation!
Thank you so much!! That was very descriptive and that made my studying easier.
Glad to hear that you liked the video Ricky Chow
Thank you for saving my exams and actually explaining what I was toiling on so hard
Happy to help! You are so welcome!
Thankyou for concisely highlighting important key points. Understanding of differences has been achieved....
Thanks for watching and you are welcome!
Excellent explanation.
+Brendon Evans Thanks! Glad you liked it!
Thanks Brendon!
Thanks.
May I pls request if you make a video about how to distinguish who you to involve and not to involve in calculating period prevalence.
Regards
Excellent Video, short and Crip! love it!.. thanks a ton for your efforts!
+Kshitij Khanna THANKS for the comment
I am watching it 2024 the best professor ever for epi and statistics
Thank you for your kind words, and happy learning!
Super helpful in studying for my biostatistics midterm! Thanks!
1That was a world class explanation!
So awesome... Should have come here to learn this a long time ago. .
From India,your explanation is marvelous.. i liked it a lot....
Glad you liked it
Many thanks for this video and all other efforts. I would like to ask about the Retrospective Cohort study ! as you mentioned it as a Prospective !
+Kahtan Thanks for the question. So Retrospective cohort studies can be a little confusing because, as you mentioned cohort studies are usually prospective. The important thing to remember is that a cohort study is always looking at a group (a cohort) who have all been exposed to an identifiable exposure and we're still wanting to know if over time, what outcomes might be associated with that exposure. In the case of a retrospective cohort study, the timeline that we follow is in the past (and we have some record of who was exposed to what and what the respective outcomes were).
Thank you for this video! I am studying for my USMLE Step 1.. THIS HELP ALOT!!!
Glad it helped Joseph Reinshagen - good luck with the exams!
Thank you so much, i was giving up on understand this topic
Happy to help!
Super simple, thank you ! Good luck
Yes, this video summed up the main points well. Just started a basic course to wrap up a M.S. in Clinical Nutrition. So, rare outcome (disease) and exposure with rare results for the exposed groups in both case control and cohort studies. Thanks.
Glad you enjoyed the video Charlien!
Wonderfully explained! Super clear. Thanks a lot.
+Camila C thanks for the feedback - much appreciated.
so good I wished I found this channel sooner
thank you so much for this video it helped me in my homework for the epidemiology class..
you provided the information in a very easy and interesting way!!
Glad I could help
Wau
Valuable information ،
thank you
Glad it was helpful! You're welcome :)
Wow amazing short and precise
+tarie ruvibez THANKS!
You saved a poor medical student from a small headache, thank you
Glad it was helpful! Thanks!
Really thanks as I get the clear explanation.
Amazing demonstration ...
thank you a lot
+abedalla h You are most welcome
Really helpful! The explanation is very easy to understand. Thank you for this educational video!
I'm delighted that you found it easy to understand. Thanks for the feedback Huy.
You did not explain the difference btween Case Control & Retrospective Cohort. Cohort has 2 types. That is the most confusing part you missed!
I have two questions to ask for those designs
1-When do we use case control study design?
2-when do we use cohort or longitudinal study design???
Thanks a lot!
You're welcome!
Thank you so much
You're most welcome
Very simplified and useful.
short and precise. Great job
This is so concise!! Thank you very much!
Thanks for the feedback. Much appreciated.
The cohort studies can be retrospective (much less common though) too. Ohterwise great summary!
True. thanks for the input. :)
Greg, this is a great supplement to my global health education, thanks so much for your time and effort.
Glad you liked the video Rory Watts - please feel free to send me any thoughts or ideas about future content for the RUclips channel.
very useful, thank you, Dr. Greg!
Hi Greg -
In Kenneth J. Rothman's textbook; "Epidemiology: An Introduction (2nd edition)", Rothman talks about "Retrospective Cohort studies" (P.85). What is your take on that? He refers to a study conducted by Morrison et al. A study on data since 15th and 16th century in Florence.
It is quite confusing (not what I needed on top of the heap of other epidemiology confusion) :P
Very helpful! Thank you!
Glad it was helpful!
Thank you soo much
Welcome 😊
Amazing Sir .. you are a perfect Teacher
Thats a really nice compliment manuboon boon - much appreciated!
great explanation :) i came here lookin for the difference between case control study and RETROSPECTIVE cohort study . unfortunately i coudnt get it
This video was very helpful. Thank you! :)
+MsZa124 you are most welcome!
wow great explaination.in such a simple way !!!!
Fantastic! I shared this with my students.
Thanks for letting me know Marjorie Simpson (much appreciated). What are you students studying (and where)? Please let them know that they are welcome to get in touch with me if they have suggestions re future video content on this channel. I also host a weekly "live" global health news roundup every Wednesday at 2pm (EST) which that might be interested in. Find out more at www.twigh.org
धन्यवाद जी।
👏👏
Super helpful, thank you
I finally understand 🤯, thank you 😭🙏🏿
Could you do a video on Attributable Risk, Absolute Risk Reduction (ARR), Number Needed to Treat (NNT), and Number Needed to Harm (NNH). These topics are all very similar and get confused. THANKS FOR YOUR VIDEOS!
Joseph Reinshagen will do.... thanks for the suggestion!!
Very helpful thanks
Thank you sir, it's a clear explanation
You're most welcome Jonathan.
Thanks, this helped me a lot!
Glad to hear it! Thank you.
Thank you very much, you solve my problem
So happy to help! Thanks
Your videos are amazing!
Glad you like them! Thanks Nida!
Helpful, thank you.
You are most welcome Misk Fahad
very clear tutorial. Thank u
Was about to subscribe... then he said, he'd regularly email me.
Very much appreciated.
Thanks Iman Awad
super explanation!
Cheers
Awesome presentation.
I appreciate the feedback. Thanks.
Thank you
This is amazing
Thank you for the feedback. Glad you enjoyed it!
Superb!! Excellent!!
Glad you liked it! :)
Outclass
Excellent explanations please add the full contents about research
Thanking you
Thanks Muhammed - will do. Happy day. Greg
Thank you so MUCH!
I read some research papers use retrospective cohort study, how about that? What's the difference?
Hey Sir thanks for this.
Hi Greg. I am confused between retrospective cohort studies and case control studies. It seems like in both situations you look at people with a disease and people without a disease and then look back at exposure?
Could you please explain the difference?
What is the difference between retrospective cohort and case control?
Very useful
Glad to hear that. Thanks!
What is the diference between case control study and a retrospective cohort study?
Thank you but What about the difference between case control and retrospective cohort study?
What is the difference between a case control and a retrospective cohort study.
So helpful
thanks - glad you found it helpful.
Dear Greg, thank you for this educational video. I have a quick question: how long would you recon a cohort study should last? If you write a thesis in about a year is it realistic? Or should it last over a number of years/decades?
Thanks for the question. The truth is that it's kinda like a piece of string... It's as long as it needs to be. That is to say, it depends on what's you're wanting to observe in your cohort. You may be looking at outcomes that take years to present (like cancer) or days (like the common cold). Hope that helps.
Really helped!
Glad you found it helpful!
What are the differences between the case-control study and a retrospective cohort study?
Really Helpfull!
Glad you liked it! :)
Great explanation sir
Rajeev Midha thanks :)
what about a retrospective cohort studies ? its seems like you have exclude their existence ?
thank you!!
You are most welcome! (thanks for the comment). :)
in cohort study; if the exposures get disease due to exposure, how did the non exposure get disease. any help
Thank youbsoo much
You are welcome
Thank you so much :D
Glad you liked it GatorGatorade
Thank you you helped me alot
Glad I could help Maryam
Great keep going man💪
It's so simple and very informative, thank you so much. I subscribed your channel. Just one little favour, can you please speak a tiny bit slowly coz English is only my second tongue.
Oversimplified but comprehensive explanation in shortest possible time.
Thank you for the feedback. 🙌
ok, so in case case control, we already have the outcome and we want to find out what exposures lead to the outcome. so this study does access temporality right
Yes, in the sense that the exposures being examined need to precede the outcome that you've identified in your cases.
i dont understand then whats the difference between a case control study and a cohort "Retrospective" study ?
Can you give us an example for sake of deeper understanding when would you choose retrospective cohort and when would you choose case-control and under which circumstence would you choose one over other for a given problem?
Hi there - if you are looking at a rare condition - lets say hypothetically, people whose hair turned blue - you might want to consider a range of possible exposures that could have caused this. You'd look at diet, exposure to sunshine, genetics, the type of shampoo that they use etc. etc. (that would be a case control study). Start with the cases and look back at possible exposures. In a retrospective cohort (as in with any other cohort) your starting point is an exposure (not an outcome). You might for example be interested in what diseases have emerged following exposure to the radiation in Japan. There might be any number of outcomes. Your cohort is the group of people exposed. In this case however, the exposure is in the past (making it retrospective). Does that make sense?
Yes i finally think i do get it . If we have a known diesese but haven't figured out the causes yet, we will go with case-control, but if we have a known cause but we yet have to proove which diesese it can cause we will go with retrospective cohort.
That's it!
Love the accent, bro