The organic chem tutor honestly deserves a Nobel prize for his endless number of lessons ... this society needs to appreciate teachers more than artists and entertainers
Just in time! You have gotten me through Chemistry, Physics, Calculus and now Stats. I’ve gotten really good grades in those past classes and I’d like to give you some credit. When I’m not a broke student I promise you I will remember the help you gave me, Mr Wahlberg.
Entering this week of stats we’re covering hypothesis testing in MATH302, without even reviewing the material this week you just taught me exactly all I needed to know to solve paired samples
Thank you so much for making this video! I wasn't able to attend my online class due to internet problems so I was really having hard time coping up with the activities. But this video helped me so much! Love from the Philippines! ❤️
I am sure you get these comments a lot judging by the ones on this video, but you are educating a generation of STEM students. Your videos have gotten me through all of calc-calc 3, statistics, and DE. I owe you more than you will ever know. Your videos have allowed an old fart like me to return to school and change the lives of myself and my family. I hope you sleep well at night knowing that you have made a lasting impact on the entire world through your videos.
When calculating 95% confidence interval, shouldn't you use t-value for 0.025, df=9( t table at 08:14). You used the t-value for 0.05 which will make it 90% confidence interval (10:53).
Brilliant presentation. I have learnt a lot from your videos Sir. On confidence interval construction, were you not supposed to use t_(9; 0.025)=2.262?
YOU HELPED ME, SOOO MUCH FOR MY ASSIGNMENT WHICH I HAD NO UNDERTSANDING AND I LOVE YOU FOR THIS VIDEO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! CAUse my lecturer was not explaining properly, the way you just did. so THANK YOU!!!!
I thank you for these works you have been doing and also for sharing your knowledge. Some of your videos clearly explain what many textbooks can not do. Please, are you hoping to deal with topics such as: factor analysis and principal component analysis? Many Thanks
No, I don't think so. I also am working on stats atm and struggled with that question. From what I have found, even when you construct a confidence interval for two-tailed tests, you still use the critical t value that corresponds to the given alpha. I think you divide alpha by two when you are finding the p-value of a two-tailed test.
the example is a one tail t test, so you dont divide alpha by 2, you can understand that from the null hypothesis, since it uses greater than or smaller than < > it should be one sided.
I did this on my own before watching the video. What I did was get the avg weight of before the program, the avg weight of after the program, and the SD from the after the weight loss program. I then used the formula and still ended up rejecting the null hypothesis. Was this approach correct? here is the data . AVG before (206.5) AVG after (193.4) SD 18.1945. I got a calcutalted t value of -2.277 which is way past the -1.833 .
Even though the t-test is one-tailed, the CI95 is bounded on both sides? Shouldn't a one-tailed CI be bounded by either negative infinity at the lower bound or infinity at the upper bound?
No, that is for a two sided t-test. In this case, we are working with a left-tailed t-test, so we use alpha as it is - 0.05 - (do not divide by 2) and 9 degrees of freedom, gives us a t value of -1.833
Yes. If the test is one sided like described in part a the upper bound should be positive infinity. But in the solution of part b two finite end points are being calculated.
Thank you for your video, it's really helpful! Do you know if the difference in mean values can also be used to quantify the effect size? Is there a separate test you could on the mean difference to quantify an effect size?
Wait, you said in 3:02 that mu_d is the sample mean difference. How come that you said mu_d is a population mean difference this time at 8:50? I'm a bit confused.
I don't think we ever say there is sufficient evidence to support the alternative....we simply say we fail to reject the null. They are two different things and quite serious
Can anyone tell me why my upper and lower values of 95% CI of the difference in SPSS are different to those in the video (-22.418 & -3.782)? All other numbers are the same, the mean, std. deviation, std. error mean, calculated t-value, and df.
Hey guys! In first place, thank you so much for the video. One question: Is it possible to use another parameter than the population mean in the hypothesis? Let's say I want to measure if the sample mean of a sports team's height is greater than a certain limit. This limit is not the population mean, but just a value established by rules. Could I run the t test?
Hey there, hopefully you see this. It's ok if you don't, I LOVE your videos, thank you so much. I was on the part when you find the Standard Deviation of the Mean of the Differences. and I found my Standard Deviation a different way; I used Sum of Squares to find the Standard Deviation - S (Standard Deviation of the Mean) = √Σ(x-Mean of Differences)^2 / N-1 (Degrees of Freedom). When I found the Standard Deviation with the variance formula, instead of your Standard Deviation, 13.025, I instead calculated 12.76. Do you also get that SD when you calculate the SD of the Mean with the Variance Formula?
I dont understand why for the weight loss, the null hypothesis isn't mewd is less than 0. Isnt the status quo that the weight loss program IS effective??
Im confused. I thought when the Statistic > critical value you reject the Null Hypothesis but you did the opposite. Please explain why because i thought this rule was consistent throughout statistics.
joseph smith In this case, the alternate hypothesis is directional, meaning that the test is one-tailed. It happens to be left-tailed because the alternate hypothesis involves a mean difference less than zero. Since it’s left tailed, the critical value is negative. The rejection region is always to the more slender side of the curve; therefore, if the critical value boundary is negative (on the left side of the curve), the rejection region is farther to the left of the critical value boundary, that is, where the curve is skinnier. This amounts to saying that the null is rejected if the test statistic is more negative than the critical value (which is itself negative in this case).
Just because I have nothing better to do I used my HP35s for a trend line and I got a r factor of +.914 which means it has a decent probability, and the m factor was .624 and b factor was 64.4 giving a formula final weight equals aprox .624*initial weight+64.4 comes close have fun...Not responsible for minor errors this is statistics!!!!
I know this is super late but why did he use the t values for 1-a and not 1-a/2 when computing the confidence interval? The way he did it he found it for a 90% confidence level no for a 95% confidence level like requested
hi thanks for the video, just need to get a point clarified when getting the confidence interval shouldn't the (Alpha /2) be used which is 0.025, But 0.05 .... because for confidence interval we usually use t(Alpha/2) right ? .... in your previous video, you mention we should be using t(Alpha/2) : th-cam.com/video/MUD390jtgQs/w-d-xo.html would you be able to advise on this ?..... Thanks, best reagards.
Next Video: th-cam.com/video/HKDqlYSLt68/w-d-xo.html
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@TheOrganicChemistryTutor shouldn’t we use t(alpha/2) to find critical value for C.I?
for confidence interval shouldn't we use the two-tail t-score, in this case "2.26" 9df?
@@shuvashishsharma1299 I was thinking the same
@@riky2107 should we use (9 and .025) or (9, 0.05), i get confused which value is correct, do we use alaph or alpha/2 in one_tailed test
The organic chem tutor honestly deserves a Nobel prize for his endless number of lessons ... this society needs to appreciate teachers more than artists and entertainers
彳亍
ur making teaching out to be way harder than it actually is
@@alexb1312 well bad math teachers have caused generation hate math for ever
he may not have a nobel but having millions sure helps too
I’m not joking when I say this man teaches me chem, ochem, physics, maths in general, calculus, physics
@Beckham Darren 15 minutes? You know what that reminds me of?
Geico. 15 minutes can save you 15%
or more on car insurance.
Thank you so much.You are talented .a good teacher.Its Annie in Zimbabwe.most lectures are failing
He is your saviour haha
Very nice explanation sir love from India
I was literally just thinking of the same thing
Just in time! You have gotten me through Chemistry, Physics, Calculus and now Stats. I’ve gotten really good grades in those past classes and I’d like to give you some credit. When I’m not a broke student I promise you I will remember the help you gave me, Mr Wahlberg.
is he the actor Mark Wahlberg??
@@mmdg1917 yess, he is. He is mark walhberg.
are you doing good financially now / graduated?
been 4 years thought I'd ask lol
Entering this week of stats we’re covering hypothesis testing in MATH302, without even reviewing the material this week you just taught me exactly all I needed to know to solve paired samples
Thank you so much for making this video! I wasn't able to attend my online class due to internet problems so I was really having hard time coping up with the activities. But this video helped me so much! Love from the Philippines! ❤️
Its amazing how i sleep and dodge lectures keeping in mind organic chemistry has got my back.....God bless you your a hero to many
I've added videos of this channel to my review list and I review them once in a while but every time I learn some new points. 👍
I am sure you get these comments a lot judging by the ones on this video, but you are educating a generation of STEM students. Your videos have gotten me through all of calc-calc 3, statistics, and DE. I owe you more than you will ever know. Your videos have allowed an old fart like me to return to school and change the lives of myself and my family. I hope you sleep well at night knowing that you have made a lasting impact on the entire world through your videos.
Forgot to add in linear algebra! I'd be toast without your hands-on videos.
This was soo hard to find! Exactly what I’ve been looking for! One sample for comparing the effectiveness of two variables!
When calculating 95% confidence interval, shouldn't you use t-value for 0.025, df=9( t table at 08:14). You used the t-value for 0.05 which will make it 90% confidence interval (10:53).
Remember, it's a one-tailed test! :-)
yea I had the same concern
@@surihapsari6595 CI is always 2-tailed
t value must be 2.262 right?
You are right, CI is always 2-tailed. He just made a mistake.
oh my god you're a lifesaver, i was so lost on all of this but i actually get it now. THANK YOU
Brilliant presentation. I have learnt a lot from your videos Sir. On confidence interval construction, were you not supposed to use t_(9; 0.025)=2.262?
Yes I thought the same thing!
Yup
i think so too
Shouldn't the null hypothesis be that the mean difference equals to zero?
This man is a science-maths teacher. Any field he is very good 👍🏾
Thank you so much! I’m a psychology student and this helps a lot
Me too, let's connect? What's your Instagram?
I am repeating what others have said here. This is exceptionally done!
Give this man a medal!
Thankyousomuch. I won't be able to answer my stats activities without your helpful tutorials. Godbless💙
YOU HELPED ME, SOOO MUCH FOR MY ASSIGNMENT WHICH I HAD NO UNDERTSANDING AND I LOVE YOU FOR THIS VIDEO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! CAUse my lecturer was not explaining properly, the way you just did. so THANK YOU!!!!
Bro taught me math in high school now he’s teaching my stats in university he never fails
I thank you for these works you have been doing and also for sharing your knowledge. Some of your videos clearly explain what many textbooks can not do. Please, are you hoping to deal with topics such as: factor analysis and principal component analysis? Many
Thanks
Hello! Please I hope someone answer I really need help. How do I know if it should be before-after or after-before?
it works either way, just make sure that the tail is facing in the corresponding direction.
God would certainly bless you with good health for your great job in educating a vast generation of academicians.
You’re the best, man!
got on the wrong bus, on my way to uni and watching your videos before class.
love your work
Don't you practice online lessons?
thank you so much for this i can use this now in my dissertation to calculate stuff !!Thanks a lot
My best online prof. Heart you Sir
You're a life saver! ❤
Wow!! Super easy to follow, awesome tutorial.
Thanks you saved my statistic exam
Appreciate your time to go over paired T test. Can you go over on SPSS because that is what my college is using instead of excel
Shouldn't we use n-1 to do the standard deviation since we're talking about samples? or are the differences not considered samples in these cases?
When do you take the absolute value of T and critical values?
Shouldn't we use .025 instead of .05 for t when we do the confidence interval?
No, I don't think so. I also am working on stats atm and struggled with that question. From what I have found, even when you construct a confidence interval for two-tailed tests, you still use the critical t value that corresponds to the given alpha. I think you divide alpha by two when you are finding the p-value of a two-tailed test.
the example is a one tail t test, so you dont divide alpha by 2, you can understand that from the null hypothesis, since it uses greater than or smaller than < > it should be one sided.
if it was a two-tail test you would use .025 on each tail, but since its left-tailed its just .05 on the one side.
Excelent video. Just commenting to boost it.
Exceptionally good....very clear and simple presentation
You're the best Mat God bless you
Many thanks for simplifying this topic.
On calculating the Confidence interval, why did you get the t critical at alpha not alpha/2?
May i ask if the question doesn’t provide the before information respectively, but give u a sample mean. Can it still be calculated?
Man, thank you one more time!! for the second year in a row your saving my ass!!
Many thanks for breaking this down.
for confidence interval shouldn't we use the two-tail t-score, in this case "2.26" 9df?
Is it always after - before?
I did this on my own before watching the video. What I did was get the avg weight of before the program, the avg weight of after the program, and the SD from the after the weight loss program. I then used the formula and still ended up rejecting the null hypothesis. Was this approach correct? here is the data . AVG before (206.5) AVG after (193.4) SD 18.1945. I got a calcutalted t value of -2.277 which is way past the -1.833 .
❤thank you, you actually save lives
how do we/you know that the grap is left or right-sided and how to know that the grap is one tail or two tail
Even though the t-test is one-tailed, the CI95 is bounded on both sides? Shouldn't a one-tailed CI be bounded by either negative infinity at the lower bound or infinity at the upper bound?
Why am I getting -21.173, -5.03 on my calculation for the confidence interval when I use the equation given by professor?
This teacher is not a human, trust me! He is a God, a life-saving God! 😢😢😢
how do I get the P-value from this?
You’re a legend
Very Good explanation.
10:50 t value must be 2.262 right?
No, that is for a two sided t-test. In this case, we are working with a left-tailed t-test, so we use alpha as it is - 0.05 - (do not divide by 2) and 9 degrees of freedom, gives us a t value of -1.833
Yes. If the test is one sided like described in part a the upper bound should be positive infinity. But in the solution of part b two finite end points are being calculated.
Thank you for your video, it's really helpful! Do you know if the difference in mean values can also be used to quantify the effect size? Is there a separate test you could on the mean difference to quantify an effect size?
Wait, you said in 3:02 that mu_d is the sample mean difference. How come that you said mu_d is a population mean difference this time at 8:50? I'm a bit confused.
Also, is this problem a one or two-tailed paired t-test?
shouldnt we have t alpha/2 since we are dealing with confidence intervals? So, ~2.26
Why is it -3.18 for Tc instead of -0.318 ? Rounding?
thanks so much for the video. you always help us. BUT the value for t is miscalculated here. CHECKING MULTIPLE T TABLES, T=2.262
Thank you so much you are superb at what you do.
Thank you so much. I found question type, which i look for, eventually.
I don't think we ever say there is sufficient evidence to support the alternative....we simply say we fail to reject the null. They are two different things and quite serious
Can anyone tell me why my upper and lower values of 95% CI of the difference in SPSS are different to those in the video (-22.418 & -3.782)? All other numbers are the same, the mean, std. deviation, std. error mean, calculated t-value, and df.
Using the CI formula in this video th-cam.com/video/TMRBGFIj0RM/w-d-xo.html gives me the same values as SPSS.
when calculating the CI you have to use t at alpha/2 so t0.025 at df = 9 which would give you these values
what if the n is more than thirty, do we still use this formula and just replace the t with z?
I have a question. what conditions we need to confirm in order to constract confidence interval?
Hi, do you know the source book/journal for paired t-test?
Hey guys! In first place, thank you so much for the video. One question: Is it possible to use another parameter than the population mean in the hypothesis? Let's say I want to measure if the sample mean of a sports team's height is greater than a certain limit. This limit is not the population mean, but just a value established by rules. Could I run the t test?
this was helpful thanks sir
Isnt the t value formula meant for an unpaired t test?? this video is on paired t test right
is it a general rule to subtract after to before (after - before)??? really need the help.
No. But in this case they wanted weight reduction so before-after would be easier to explain
hi, may I ask if the sample size data of before and after is not the same, how can I solve this?
Thank you, It really is helpful.
Bro how to choose one tail or two tail for sample distribution
Hey there, hopefully you see this. It's ok if you don't, I LOVE your videos, thank you so much.
I was on the part when you find the Standard Deviation of the Mean of the Differences. and I found my Standard Deviation a different way; I used Sum of Squares to find the Standard Deviation - S (Standard Deviation of the Mean) = √Σ(x-Mean of Differences)^2 / N-1 (Degrees of Freedom). When I found the Standard Deviation with the variance formula, instead of your Standard Deviation, 13.025, I instead calculated 12.76. Do you also get that SD when you calculate the SD of the Mean with the Variance Formula?
Very well done thanks.
It helped a lot🙏🙏
I dont understand why for the weight loss, the null hypothesis isn't mewd is less than 0. Isnt the status quo that the weight loss program IS effective??
Exactly my thought. Doesn't make much sense
How can I calculate it by using the calculator
Im confused. I thought when the Statistic > critical value you reject the Null Hypothesis but you did the opposite. Please explain why because i thought this rule was consistent throughout statistics.
joseph smith In this case, the alternate hypothesis is directional, meaning that the test is one-tailed. It happens to be left-tailed because the alternate hypothesis involves a mean difference less than zero. Since it’s left tailed, the critical value is negative. The rejection region is always to the more slender side of the curve; therefore, if the critical value boundary is negative (on the left side of the curve), the rejection region is farther to the left of the critical value boundary, that is, where the curve is skinnier. This amounts to saying that the null is rejected if the test statistic is more negative than the critical value (which is itself negative in this case).
no it depends on the test used
Hello. It is possible to use paired t-test if I get the mean scores of before and after, not its total scores?
Very valuable thank you so much
Sometimes we do (after - before) and sometimes (before - after) ... what tge reason?
You are the greatest
Wilcoxon rank sum test ?
Just because I have nothing better to do I used my HP35s for a trend line and I got a r factor of +.914 which means it has a decent probability, and the m factor was .624 and b factor was 64.4 giving a formula final weight equals aprox .624*initial weight+64.4 comes close have fun...Not responsible for minor errors this is statistics!!!!
the standard deviation i get on my calculator ( because i can input it there) is 12.3. idk why im always a few points off when it i do it that way
Did you use the Sample Stdev?
@@justinmulyagananda1057 yes i got 12.3 too, i used the general standard deviation formula, is it wrong?
I know this is super late but why did he use the t values for 1-a and not 1-a/2 when computing the confidence interval? The way he did it he found it for a 90% confidence level no for a 95% confidence level like requested
Anyone know why null is >=0 not =0? I thought null was about no change.
Thank you Sir.Greatful to u
thank u for this
hi thanks for the video, just need to get a point clarified when getting the confidence interval shouldn't the (Alpha /2) be used which is 0.025, But 0.05 .... because for confidence interval we usually use t(Alpha/2) right ? ....
in your previous video, you mention we should be using t(Alpha/2) : th-cam.com/video/MUD390jtgQs/w-d-xo.html
would you be able to advise on this ?.....
Thanks,
best reagards.
Ishan Chathuranga nah cuz it’s 1 tail
@@bffchannel9860 thanks 👍
Thank you very much!
What if t value is in negative
How do I pay my tuition fee?
Thank you so much,God bless
Why is the significance level changing from 5% to 0.05
cause its 5% of 1
Thank you so much
Qusetion ? Ha : is greater than 0 because before was heavy large number minus after smaller weight gives numbers above zero
when I calculate SD I am getting a different value