00:02 Understanding confounding and effect modulation in medical studies. 01:55 Understanding confounding vs. effect modulation 04:01 Smoking can affect the outcome, exposure, or both, impacting the study findings. 06:08 Confounding affects both exposure and outcome in research studies. 08:19 Understanding key methods for comparing means in research studies 10:11 Chi-square is used to compare proportional data 12:05 Understanding analysis of variance and t-tests 14:06 Understanding effect modulation vs. confounding 15:59 Understanding Number Needed to Treat (NNT) 17:38 Understanding of absolute reduction and number needed to treat 19:21 Effect modulation vs. confounding in research.
Hi everyone, indeed dr randy neil did come down from heaven ! May God bless him on this Friday where ever he is now ...his unique flavor in teaching touched many dr's preparing for the usmle ...
I will post my situation here , as I'm preparing for my usmle , I'm also applying for jobs in clinical research , residency is going be competitive, your thoughts dr randy neil is appreciated as always ...
Thanks Randy. Just to clarify (min 13:30): if the CI does not include zero is significant for a mean value. If CI does not include 1, is significant for OR or RR. : )
This is exactly what confused me! Thanks for pointing it out. Aren't we talking about the RR here as well? So how do we day its significant even though it includes 1? 🤔
Thank you Dr Neil. Im in my first semester of my post grad studies Epidemiology and Biostatistics. Am currently learning Biostastics online (due to the pandemic) and it was just terrible. I couldn't nor understand grasp the calculation concepts at all. I came on RUclips to look into Biostastics for dummies but came across your channels. Aren't I glad I did! I have been online all day going through your videos and I can say am confident that I can pass my biostat exams. Within a day am now very conversant with how to handle questions starting form the question part, before going through any long prose. I now know what formula to apply in a ,majority of the questions be it NNT, PPV, LR, AR%, when to draw the chi square among others. Thank you so so much. Your videos are extremely helpful. If you could do some videos on Correlation coefficients, confidence intervals and hypotheses, that would be great. So far, am grateful. I have a few questions to share with you for the purpose of helping me and the rest here learn better too. I'm not sure how to do so though. TIA
Dr. Neil is key to success. Thank you for everything you do and for posting these videos. No test prep company or any professor ever explained this to me. You are a true gift to the world. Thank you for sharing your knowledge.
Going through your videos my step 3 is Just a week way.. your videos have made these calculations so easy to understand.. thank you very much and i hope i score well
I always watch your stats videos and genetics video before y FRCOPH exams. They are such immense help. I cant thank you enough. sending you lots of virtual flowers and wishes.
this is an amazing video! I kept getting these chi-square questions wrong over and over because I wanted to do it the "proper" school way. Dr. Randy you're a godsend! thank you thank you. Step 1 this Wed!
hi dr. can you please do videos on... a. linear regression vs logistic regression b. kaplan meyer curve c. forest plot d. population pyramid p.s thankyou for your videos:)
Michelle, You are nervous because it means something to you... STAY POSITIVE, STAY STRONG... Everything ha already been determined LONG AGO so NO NEED TO WORRY...
In the NNT problem, I believe you had labeled the graph correctly. If we are calculating EVENT RATE, then that means we are calculating who had hair loss in the control group minus who had hair loss in the treatment group. Please correct me if my concept is wrong though my step is in a few days LOL
had this exact thought... when i calculated it before he changed the labels i got the correct answer then he changed them and i got confused!!!! Thank god im not the only one
First aid has NNT listed as NNT = 1/ ARR with ARR = (c/ (c + d)) - (a/ (a + b)). When I solved the problem using the formula from first aid, I got around 4.2 for my answer. I'm a bit confused on the formula you used to tackle the last problem.
if only you would be teaching pharmacist for their board exam, they would have passed on a first try with flying scores. thank you for putting time and creating these videos to help us better understand confusing concepts .
wow ! .. actually it should be woowooowoowooowooowo ! u made it like super easy within 22 min video ! I wana be your life long student , Sir . u r really great , hero of biostat I must say . i think everyone will agree with me too.
Wow , great explanations and made so easy to understand the concept in ridiculously short time , Dear Dr kindly upload a Neuro video of high yield topics for step 1. Thanking you in anticipation 😊
your videos have been so amazing thank you for your hard work! hoping you have time to upload a short one on population pyramid. happy holidays doctor Randy !
Always hated biostats, was never any good at it. Thank you SO much for these simplified videos! Made it super easy! Can't thank you enough! I'm still can't get what's a good confidence interval value and why.
For the most part...think...the Confidence interval that doesn't contain the number "1" is good... 0.55-0.86 is good.... 1.2-3.5 is good... 0.9-1.1 is NO good...
is there a mistake ? For the question with smoking and prostate ca, if the p values were not statistically significant due to the p-vaules doesn't it mean the results are not valid in the stratification and that there is NO difference, no effect mod, and No confounding? thx
I was thinking the same that when one study is so statitically insignificant, how can we base our assumptions on that. Rather, it might be that the researcher had the predilection towards proving the association between the drug and DVTs, so he carried out an insignificant study to support his belief. In that case, the right answer would be 'confirmation bias'.
A better explanation of chi squared would be that it's comparing two data sets where both the independent and dependent variable are categorical (vs categorical independents and measured dependent variables)
i dont understand the 2nd question on confounding and effect modulation. in the second half of the question statement where they corelated the effects of smoking with both alcohol consumption and pancreatic cancer the test results are of no significant value. both are more than acceptable 0.05. meaning that smoking is not related to either of them.
Hi Dr Neil, I have a question regarding Q2, in second part of the question the P value is high so wouldnt that means it is not significant and hence being a smoker or a non smoker doesnt really make a difference? am I missing out something here or am I not getting something and I have spoken something beyond stupidity? Would be nice if you shed a light on this. Thank you so much for your videos your work is wonderful!
Amazing! Thank you so much, specially the ANOVA, T test, and chi square!. I had a question about Q2 however; if they re-examnined the findings, and found that smoking/nonsmoking was only associated with a increase/decrease in smoking, wouldnt that be an effect modification as it only affects the outcome (of pancreatic cancer), and not the exposure (alcohol)? I am a little confused on that one
Saba, Thank you for the question... The take home point is that we know there is an association with BOTH exposure and outcome (for Confounding)...and only with OUTCOME for effect modulation. Everything else is "smoke and mirrors". Just take a step back and see it "big picture"... not sure if I am making sense...but for now, just know principle between the two.
Hi Dr. Neil. one more question : A 26 year old medical student comes to the physician with a 3 week history of night sweats and myalgias. During this time, he also had a 3.6 kg weight loss. He returned from a month tropical medicine rotation in Cambodia 1 month ago. A chest x ray shows reticulonodular opacities suggestive of TB. The student is curious about his likelihood of having active TB. He reads a study that compares sputum testing results between 2800 patients with likely active TB on a basis of history, clinical symptoms and CXR pattern and 2,400 controls. The results are: Active TB likely on basis of History, clinical and CXR Active TB not likely on basis of History, clinical and CXR Sputum Test positive 700 300 Sputum Test Negative 2100 2100 What is the probability that a patient with a diagnosis of active TB on the basis of history, clinical symptoms, and CXR pattern actually had active TB? The actual answer is 0.25. But my calculation is 0.70. Would you please explain this? Thank you
Hi, the given table is the confusing aspect. They gave you the flipped table. The top heading should be the gold standard (Sputum test) and the side heading should be for the test conducted ( History, clinical and CXR) . You should rearrange and construct the chart like this: Sputum Test positive Sputum Test Negative Active TB likely on basis of History, clinical and CXR 700 2100 Active TB not likely on basis of History, clinical and CXR 300 2100 Then, PPV is 700/(700+2100) = .25
Smoking affects exposure AND outcome (both of these variables) which is by definition CONFOUNDING BIAS. People who drink alcohol may also smoke (distorting exposure values) and people who smoke may also get pancreatic CA (distorting outcome values). This cumulatively distorts the relationship bridge between smoking and pancreatic CA and confounds the results. Smoking is an effect modulator with DVT as it only affects the outcome which is by definition EFFECT MODULATION. Think about it...smokers are vasculopaths who are inherently in a hypercoagulable state and thrombose easily) but there is NO clear association between the NMDA drug and smoking.
These videos are awesome ❤️👏🏻 i just wanna ask u if we compare two mean values , when will it be regression analysis and when will be it two sample t test?? Because its so confusing
Hi Dr.Neil, can you do a video that involves the large 2 page pharm ads and how to navigate that? I get so intimidated. I'm trying to take the step III asap....my confidence needs the most work.
Hi Dr. Neil, thank you for the videos. Would you please explain this problem: A recent study was conducted to assess the intelligence of students enrolled in an alternative high school program. The results showed the IQs of the students distributed according to the normal curve, with a mean of 115 and a SD of 10. Based on this information it is most reasonable to conclude that a) 50% of the students will have the IQ below the standard mean of 100 b) 50% of the students will have the IQ below 105 c) Students with IQs of 125 are the 84th percentile d) 2.5% of the students will have IQs greater than 125 The answer is b. Would you please explain where did 84th percentile come from? Thank you!
That is a rule of thumb: Mean +- 2SD = 95% confidence interval Mean +- 1SD = 66,6% CI In a Normal Distribution, mean = median = p50 An IQ of 125 is the mean + 1SD. So it is p50 + (66,6/2) = 83.3% (roughly 84%). We divide 66.6 by 2 because we are only adding 1SD, not adding and subtracting, get it? Remember: - 2SD = p5 - 1SD = p17 Mean = p50 + 1SD = p83 + 2SD = p95 + 3 SD = p99
![Seungmin "그렇게, 천천히, 우리(As we are)" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/kAzmhLHePqU/mqdefault.jpg)
00:02 Understanding confounding and effect modulation in medical studies.
01:55 Understanding confounding vs. effect modulation
04:01 Smoking can affect the outcome, exposure, or both, impacting the study findings.
06:08 Confounding affects both exposure and outcome in research studies.
08:19 Understanding key methods for comparing means in research studies
10:11 Chi-square is used to compare proportional data
12:05 Understanding analysis of variance and t-tests
14:06 Understanding effect modulation vs. confounding
15:59 Understanding Number Needed to Treat (NNT)
17:38 Understanding of absolute reduction and number needed to treat
19:21 Effect modulation vs. confounding in research.
Thank you...
@@RandyNeilMD no problem sir
Man, these videos are gifts from the divine. Thank you, Dr. Neil!!
Sky, You are most welcome. Glad it was helpful.
How is there not millions of views on this. I tried EVERYTHING to understand and remember biostats. THIS DID IT FINALLY.
Wohoo!! Perfection!!
Thank you, SIR!!!!
future doctors owe it to you.
Help the next guy in line...
Hi everyone, indeed dr randy neil did come down from heaven ! May God bless him on this Friday where ever he is now ...his unique flavor in teaching touched many dr's preparing for the usmle ...
Thanks Jameel... Appreciate the kind words! KEEP STUDYING HARD!!
By any chance , is it OK to share your email, any case any dr want to reach out and seek your advice on any matter relating to their journey!
I will post my situation here , as I'm preparing for my usmle , I'm also applying for jobs in clinical research , residency is going be competitive, your thoughts dr randy neil is appreciated as always ...
@@jameelashkar9244 sure... randy.neil8@gmail.com
Thanks Randy.
Just to clarify (min 13:30):
if the CI does not include zero is significant for a mean value.
If CI does not include 1, is significant for OR or RR. : )
This is exactly what confused me! Thanks for pointing it out. Aren't we talking about the RR here as well? So how do we day its significant even though it includes 1? 🤔
Thanks, Dr. Neil for your dedication and help to all of us!
Thank you Dr Neil. Im in my first semester of my post grad studies Epidemiology and Biostatistics. Am currently learning Biostastics online (due to the pandemic) and it was just terrible. I couldn't nor understand grasp the calculation concepts at all. I came on RUclips to look into Biostastics for dummies but came across your channels. Aren't I glad I did! I have been online all day going through your videos and I can say am confident that I can pass my biostat exams. Within a day am now very conversant with how to handle questions starting form the question part, before going through any long prose. I now know what formula to apply in a ,majority of the questions be it NNT, PPV, LR, AR%, when to draw the chi square among others. Thank you so so much. Your videos are extremely helpful. If you could do some videos on Correlation coefficients, confidence intervals and hypotheses, that would be great. So far, am grateful. I have a few questions to share with you for the purpose of helping me and the rest here learn better too. I'm not sure how to do so though. TIA
Clara, Glad it was helpful...
Thank you so much. Tying to beat this beast of an exam is not easy, so these videos are a lifesaver!
Glad it has been helpful.
Dr. Neil is key to success. Thank you for everything you do and for posting these videos. No test prep company or any professor ever explained this to me. You are a true gift to the world. Thank you for sharing your knowledge.
Thank you for the kind words... KEEP MOVNG FORWARD. Keep me posted...
Going through your videos my step 3 is Just a week way.. your videos have made these calculations so easy to understand.. thank you very much and i hope i score well
Went well?
Gift from God. Thank you for making these concepts simple!!!
Thank you for the kind words Yash
Great, short and succinct. Thank you, Professor Neil!
Amazing Video for Step 2 CK!
You are welcome.
I always watch your stats videos and genetics video before y FRCOPH exams. They are such immense help. I cant thank you enough. sending you lots of virtual flowers and wishes.
Thank you Kiva for the kind words.
Thank you so much another extraordinary video on biostatatistic, you are remarkable Dr.neil.
Musawair, Thank you for your support. Much appreciated.
Amazing video. Your dedication to medical field is greatly appropriated!
Princess, Thank you for the comment.
Great job Dr.Neil ,simply amazing.Huge respect for u
Mish, Thank you for the comment
this is an amazing video! I kept getting these chi-square questions wrong over and over because I wanted to do it the "proper" school way. Dr. Randy you're a godsend! thank you thank you. Step 1 this Wed!
The best way in learning is to solve questions! Thanks for making it easy
Asmaa, Glad it was helpful.
Your amazing i feel so much confident about what I've learned , so very greatful.
Thank you for commenting
You are the best out there, Dr Neil. Stay awesome ⭐️
Thank you... I do appreciate the feedback.
just found ur videos one month b4 my exam and stats were my weakest subject and its the oppsite now
PERFECT!!
hi dr. can you please do videos on...
a. linear regression vs logistic regression
b. kaplan meyer curve
c. forest plot
d. population pyramid
p.s thankyou for your videos:)
Thanks for the topics... I will definitely look to see if I have those in the library... You are putting me to work.
ruclips.net/video/ulk_JWckJ78/видео.html
Dr Neil No words can describe about your teaching :)
Thank you Chetan... Hope you are staying focused and studying HARD!!
I needed this!!! Taking Step 1 soon and Im super nervous and anxious about it
Thank you for this videos!!
Michelle, You are nervous because it means something to you... STAY POSITIVE, STAY STRONG... Everything ha already been determined LONG AGO so NO NEED TO WORRY...
Thank you for being so thorough. Your work is amazing as expected 😉
Thanks Jolie, You are always very kind with your comments.
Dr. Neil these videos are amazing. Thanks for the great explanations!
Glad it was helpful.
This video is super helpful Dr Randy! Thank you so much.
Anusha, You are most welcome.
Thanks Dr.Neil. I have tried alot sources but yours was best one.
Thank you for the comment.... Glad it has been helpful.
Ur videos have been of great help to me in my biostatistics/epidemiology 👍
Ikechukwu, Thank you for taking time to comment. Glad it was helpful...
In the NNT problem, I believe you had labeled the graph correctly. If we are calculating EVENT RATE, then that means we are calculating who had hair loss in the control group minus who had hair loss in the treatment group. Please correct me if my concept is wrong though my step is in a few days LOL
I'm confused as well
You are Correct👍🏼
Legend
had this exact thought... when i calculated it before he changed the labels i got the correct answer then he changed them and i got confused!!!! Thank god im not the only one
I felt the same for a while until I rewatched to realise we're asked NNT to PREVENT hair loss. So its for those with NO hair loss!
First aid has NNT listed as NNT = 1/ ARR with ARR = (c/ (c + d)) - (a/ (a + b)). When I solved the problem using the formula from first aid, I got around 4.2 for my answer. I'm a bit confused on the formula you used to tackle the last problem.
Hey, just wondering if there is any follow up on your query?
if only you would be teaching pharmacist for their board exam, they would have passed on a first try with flying scores. thank you for putting time and creating these videos to help us better understand confusing concepts .
Par Rez, Thank you for taking time to comment. I am humbled by your comments.
why for the last question when the equation was control - treatment, you put the new treatment data - the placebo ?
wow ! .. actually it should be woowooowoowooowooowo ! u made it like super easy within 22 min video ! I wana be your life long student , Sir . u r really great , hero of biostat I must say . i think everyone will agree with me too.
Taz, As long as we are all moving towards getting through these exams (STEP 1, 2, 3) then we will make whatever video topic is needed.
Thanks a lot Dr. Neil!! I am very much relieved now
Perfect.
This video saves my life. Thank you so much sir.
Glad it was helpful.
Wow , great explanations and made so easy to understand the concept in ridiculously short time , Dear Dr kindly upload a Neuro video of high yield topics for step 1.
Thanking you in anticipation 😊
Ahtesham, Thank you for commenting. I will eventually make my way to NEURO... I'll have to look back and see what I have. Appreciate the comment.
your videos have been so amazing thank you for your hard work! hoping you have time to upload a short one on population pyramid. happy holidays doctor Randy !
Michael. You are putting me to work...
Thank you 😊.I was so confused about confounding,this was helpful.
Glad it was helpful!
Always hated biostats, was never any good at it. Thank you SO much for these simplified videos! Made it super easy! Can't thank you enough! I'm still can't get what's a good confidence interval value and why.
For the most part...think...the Confidence interval that doesn't contain the number "1" is good... 0.55-0.86 is good.... 1.2-3.5 is good... 0.9-1.1 is NO good...
@@RandyNeilMD Oh okay, thanks alot!
Your videos should be an A plus resource for biostats in the First Aid section for biostats :)
Ali, Thank you for the kind words.
Great video agan. Got a lot of these in the USMLEs
PERFECT. It WILL be out strength.
is there a mistake ? For the question with smoking and prostate ca, if the p values were not statistically significant due to the p-vaules doesn't it mean the results are not valid in the stratification and that there is NO difference, no effect mod, and No confounding? thx
I was thinking the same that when one study is so statitically insignificant, how can we base our assumptions on that. Rather, it might be that the researcher had the predilection towards proving the association between the drug and DVTs, so he carried out an insignificant study to support his belief. In that case, the right answer would be 'confirmation bias'.
You were probably talking about Q#2, but yeah same point in Q#1.
These are super clear to learn. Thank you very much
Chinthaka, You are most welcome.
Thorough as always! Thank you!
Bork Boi, Thank you for your continued support.
Thank you so much, Dr. Neil!
A better explanation of chi squared would be that it's comparing two data sets where both the independent and dependent variable are categorical (vs categorical independents and measured dependent variables)
i dont understand the 2nd question on confounding and effect modulation. in the second half of the question statement where they corelated the effects of smoking with both alcohol consumption and pancreatic cancer the test results are of no significant value. both are more than acceptable 0.05. meaning that smoking is not related to either of them.
I have the same doubt
Hi Dr Neil, I have a question regarding Q2, in second part of the question the P value is high so wouldnt that means it is not significant and hence being a smoker or a non smoker doesnt really make a difference? am I missing out something here or am I not getting something and I have spoken something beyond stupidity? Would be nice if you shed a light on this. Thank you so much for your videos your work is wonderful!
I have been having the same doubt. Hope Dr Neil replies!
Thank you Dr. Neil!
You are most welcome.
So grateful for you Prof!
My pleasure!
similar to Uworld step 1 Qs. # 1173. Thank you for that clarification.
Awesome Dr Neil!
Thank you Obinna
Thank u sooooo much .. no words 😶 to say....this is very very good....
USMLE Goal, Thank you for the comment
YOU'RE THE BEST! Thank you!
Thanks Ryan, Appreciate the comment.
Sos un salvavidas, Dr Neil.
Amazing! Thank you so much, specially the ANOVA, T test, and chi square!. I had a question about Q2 however; if they re-examnined the findings, and found that smoking/nonsmoking was only associated with a increase/decrease in smoking, wouldnt that be an effect modification as it only affects the outcome (of pancreatic cancer), and not the exposure (alcohol)? I am a little confused on that one
Saba, Thank you for the question... The take home point is that we know there is an association with BOTH exposure and outcome (for Confounding)...and only with OUTCOME for effect modulation. Everything else is "smoke and mirrors". Just take a step back and see it "big picture"... not sure if I am making sense...but for now, just know principle between the two.
@@RandyNeilMD thank you!
Fantastic video! Thank you!
You are most welcome.
Hi Dr. Neil. one more question :
A 26 year old medical student comes to the physician with a 3 week history of night sweats and myalgias. During this time, he also had a 3.6 kg weight loss. He returned from a month tropical medicine rotation in Cambodia 1 month ago. A chest x ray shows reticulonodular opacities suggestive of TB. The student is curious about his likelihood of having active TB. He reads a study that compares sputum testing results between 2800 patients with likely active TB on a basis of history, clinical symptoms and CXR pattern and 2,400 controls. The results are:
Active TB likely on basis of History, clinical and CXR Active TB not likely on basis of History, clinical and CXR
Sputum Test positive 700 300
Sputum Test Negative 2100 2100
What is the probability that a patient with a diagnosis of active TB on the basis of history, clinical symptoms, and CXR pattern actually had active TB? The actual answer is 0.25. But my calculation is 0.70. Would you please explain this? Thank you
Hi, the given table is the confusing aspect. They gave you the flipped table. The top heading should be the gold standard (Sputum test) and the side heading should be for the test conducted ( History, clinical and CXR) . You should rearrange and construct the chart like this:
Sputum Test positive Sputum Test Negative
Active TB likely on basis of History, clinical and CXR 700 2100
Active TB not likely on basis of History, clinical and CXR 300 2100
Then, PPV is 700/(700+2100) = .25
THANKYOU for another amazing video :)
Sarah, Thank you for the comment. You are most welcome.
Every video is so amazing 🔥🎉
Thank you WW
Hi Randy, great videos. In the second question I still don’t understand why smoking is a confounder bias rather than effect modulation.
Smoking affects exposure AND outcome (both of these variables) which is by definition CONFOUNDING BIAS. People who drink alcohol may also smoke (distorting exposure values) and people who smoke may also get pancreatic CA (distorting outcome values). This cumulatively distorts the relationship bridge between smoking and pancreatic CA and confounds the results.
Smoking is an effect modulator with DVT as it only affects the outcome which is by definition EFFECT MODULATION. Think about it...smokers are vasculopaths who are inherently in a hypercoagulable state and thrombose easily) but there is NO clear association between the NMDA drug and smoking.
These videos should be on “Top videos” on RUclips.
You are too kind...
Nice concept explanation thank you
You are welcome
Shouldn’t we put hair loss/ no hair loss on top of the chart and tx/no tx aside in NNT question? Thank you.
The table in the NNT calculation is flipped. Exposure(new med) should be at the left side(rows)
You are a blessing.🙏👏
Thank you for the kind words.
Thanks for the video. God bless you immensely. Please can you do a video on hazard ratio
Genesis, Thank you for the comment... Yeah, I should have put a question about HAZARD RATIO... let me see what i can find.
Thank you Dr. Neil
You are most welcome Amrinder.
thanksssssssssss a TON dr Neil,
Syed, You are MOST welcome...
Thanks a alot for the video.
If data is significant, can a question ask to choose between p value of 0.05 vs 0.03?
Only if they would say which was better... less chance for error... you'd choose 0.03
Randy you have great hands
I work out...
These videos are awesome ❤️👏🏻 i just wanna ask u if we compare two mean values , when will it be regression analysis and when will be it two sample t test?? Because its so confusing
thankyouuuu dr Neil!!!
You are welcome Zuha.
Thank you Dr. Please can you make quick vedio for the p value
Hi Dr.Neil, can you do a video that involves the large 2 page pharm ads and how to navigate that? I get so intimidated. I'm trying to take the step III asap....my confidence needs the most work.
So Randy if any time i see a confidence interval containing 0 decimals something i will cross that CI because of no significance?
Hey Randy could you please explain relative risk reduction RRR=1-RR but I got lost with the words..can you just explain with an example?
awesome simply awesome
Thank you Simran.
it was really helpful,thank you!
You are most welcome.
You are the best ❤
Thank you
hello Dr.Randy Neil, how can I get notes for your stats lectures?
love every vid u made
Thank you for taking time to comment.
Hey Randy! Which textbook do I use for bio stats ?
Thank you
Arimeto, Not sure I know of one...
I'm giving my Step 3 exam in 1 month!! I hope I pass!! I'll come back once i get my results.
STAY FOCUSED, STAY POSITIVE... YES, keep us posted.
You're amazing!
Thanks.
@Dr. Neil: Where have you been all my life?
For several years I watched RUclips preparing for STEP 1... :)
Thank you so much, God bless you
You are most welcome.
Hi Dr. Neil, thank you for the videos. Would you please explain this problem:
A recent study was conducted to assess the intelligence of students enrolled in an alternative high school program. The results showed the IQs of the students distributed according to the normal curve, with a mean of 115 and a SD of 10. Based on this information it is most reasonable to conclude that
a) 50% of the students will have the IQ below the standard mean of 100
b) 50% of the students will have the IQ below 105
c) Students with IQs of 125 are the 84th percentile
d) 2.5% of the students will have IQs greater than 125
The answer is b. Would you please explain where did 84th percentile come from? Thank you!
That is a rule of thumb:
Mean +- 2SD = 95% confidence interval
Mean +- 1SD = 66,6% CI
In a Normal Distribution, mean = median = p50
An IQ of 125 is the mean + 1SD. So it is p50 + (66,6/2) = 83.3% (roughly 84%). We divide 66.6 by 2 because we are only adding 1SD, not adding and subtracting, get it?
Remember:
- 2SD = p5
- 1SD = p17
Mean = p50
+ 1SD = p83
+ 2SD = p95
+ 3 SD = p99
Thank you so much 😊
Menekse, You are most welcome.
I don’t understand confidence interval can someone explain 🥺🥺
Thanks always sir!
Appreciate your comments.
Thank you sir.. ☺️
I feel like uworld explanations will mess me up, (after i get the Q right )after watching and learning everything i need to from Dr Randy.
Sameen, Thank you for the kind words.
I try to go back and like as many videos as I can on this channel. You are an angle. I got a 72 percent on my block and all Ive done are your videos!!
what is conformation bias ?
Awesome!!
Thank you Suryasnata
Very well explained
Shalvin, Thank you for the feedback... much apprecaited.
Thanks this is helpful
Hello Dr. Neil, I just discovered your amazing videos. I have some questions, is it possible to email you?