Confidence Interval for a population mean - t distribution

[@alejandromosqueda724]

Your videos broke so many topics down for me to where I could easily understand! Saved me so much time on my homework. Thank you!

[@joshemman]

Thank you so much @alejandromosqueda724 for your kind gesture. Much appreciated.

[@bobu5213]

I don't understand why other videos on youtube don't explain every term they use even when they are labeled as "beginner" or "non-technical". You are a great teacher and I want to thank you for giving me such a clear understanding of this in barely 7 minutes.

[@joshemman]

My pleasure, @BoBu. Thanks for dropping a note,.

[@jackhouston1917]

Legend. Only video I've found that explains confidence intervals involving t-distributions and does it even better than my lecturers!!

[@joshemman]

Glad you found it helpful! 🙏

[@jackhouston1917]

@@joshemman Very much so i think i owe passing my exam to you sir

[@Petit-crochets]

I have a statistics paper this monday I couldn’t understand wat my lecturer had taught at all but thank God I got this channel…hoping to get it right in the paper thanks so muvh

[@joshemman]

All the best on your paper, Rhoda.

[@ATR2400-2]

it seems so simple retrospect. I don't know how I had so much trouble with it. Thanks for the help!

[@IgnatiusSathasivam]

The excel formulas you suggested in both videos are priceless.

[@joshemman]

Glad to hear, Ignatius.

[@akhileshbajpai765]

Soothing voice with, to the point conceptualization makes life easy. Thank you so much

[@uzmataskeen7025]

agree

[@uzmataskeen7025]

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[@triptee3449]

Thank you so much, this video cleared up all confusion i had regarding this topic. You are an excellent teacher!! Keep it up.

[@afrolitious7930]

Thank you so much. My lecturers cannot explain anything.

[@swapnilpradhan9543]

Yes. Teachers are the worst people in the world

[@amyblizzwords3650]

Seriously they don't

[@hytee7159]

Thank you very much! I have an exam tomorrow and your videos are so easy to understand. Great teacher!

[@shubhamshah5155]

you are awesome buddy thanks for the videos i cant understand a thing my professor teaches!

[@robcantrell]

Thank you, this is a clear explanation of the topic. Very helpful and great job!

[@NkopodiNkadimeng-cp1xn]

Why are we still using the t table on the second example if the n is greater than 30 and the standard deviation is known ? ... Thank you, sir you made using the t table easy and understandable

[@joshemman]

Some courses use Z when n > 30, but not everyone does. Some use t whenever σ is unknown irrespective of the size of n.

[@agusnoviana]

this channel i give me best tutorial for understanding statistic... thank a lot.. GBU

[@joshemman]

🙏

[@jemshussdsbc4775]

Realy you are the great lecturer thanks alot.

[@asamoah-danquahstanislaw2002]

You literally saved me. Thanks man 🙃

[@Mma_JC]

Wonderful... thanks a lot. I totally understand it now😊

[@joshemman]

You're welcome 😊

[@alial-qasim2453]

Thank you so much you are a savior 🙏🏻

[@priyambadapreeti1621]

You are great sir ❤❤❤

[@inhdung4521]

Where the heck have you been in my life? I literally will have the final test 6 days left, and you showed up just in time and taught me more than anything my lecturer tried to say in 15 weeks :< Sometimes, I hate the wrong timing in the right situation like this. 😕

[@uzmataskeen7025]

me too man me too

[@uzmataskeen7025]

i scored 8 marks in a 35 marks test lmfao i really was sucking at stats until i found this channel

[@Alihaidari911]

soo amazingly perfect way of teaching

[@sameeianaz1223]

Wish I had a teacher like this in uni

[@uzmataskeen7025]

us

[@davianoinglesias5030]

😅you are saving lives out here

[@chinyerechima2728]

awesome. excellent clarity

[@joshemman]

Thanks, Chinyere.

[@ali_hussain8772]

Great sir... Its very helpful We got it easily❤

[@joshemman]

Great 👍 Thanks.

[@zaidal-qadhi826]

Thank you very much for these amazing videos. I also have a related question to this material. let's say I have the following test observations for life spans of a machine (292,773 - 236,499 - 189,796 - 209,782), what is value ( which ensures that there is a 95% possibility of survival (reliability)) with 95% confidence? and how to calculate it? Again thank you very much in advance.

[@rasikarajapaksha40]

Thanks a lot ❤

[@السيوايكيكي-ت3ص]

This is what l’m looking for , thank you very much ♥️

[@joshemman]

You’re welcome 😊

[@kirmada-t8q]

so so good

[@Kanikachauhan3]

Thank you so much sir It's really helpful

[@gentesipam3895]

Thanks, can you shade more light on the aspect of t-distribution verse F-distribution while tagging +-30 sample mean.

[@Alihaidari911]

thank you so much

[@salomluvinga8850]

Thank you so much again, sir

[@veerakanneboina8086]

But we got two critical vakues one is positive and one is negative, but why only considered positive.

[@sabrinasaad8381]

life made easy!!

[@gentesipam3895]

I think, instead of trial and error, use a lower confidence level (

[@studypurpose7804]

WOw, Thank you.

[@ChristabelObum]

Hii, so when do we use the t distribution and when do we use the z distribution??

[@joshemman]

I will suggest you follow what your course/textbook says. Some use Z when σ is known. Others use Z whenever n ≥ 30. Some use t when σ is unknown. Others use t whenever n < 30.

[@hestiluhsuprobowati8143]

So, regardless sample size, in the event only sample mean is known(and sd sample) we use t-table all the way?

[@joshemman]

You have to check with your course. Some people use Z whenever the sample is large.

[@laulau4367]

His question was my question too. So for the second example you used, if someone used the z-table since the sample size was large, he should get the same answer as you received for that problem?@@joshemman

[@joshemman]

@@laulau4367 For large sample, the answer will be close for both t and z but not exactly the same. Some courses use z for large samples and some don't.

[@laulau4367]

Thank you!@@joshemman

[@JAG_158]

Explain Why it is a TWO TAIL (0.025) and not One Tail (0.05). Much appreciated

[@joshemman]

By default a 95% confidence level is located in the middle of the distribution, leaving 0.05 area which is divided equally (.025) into the two tails.

[@JAG_158]

@@joshemmanif i could rephrase, there are a few questions i’ve seen where one tail (a) is used instead of (a/2) such as a below or above average comparison. Could you explain when that is used?

[@joshemman]

@@JAG_158 See if this helps: kzbin.info/www/bejne/f6eUg4Skn7tgZ7c

[@JuyamaeMontelibano]

what if the standard deviation is unknown?

[@joshemman]

If the population standard deviation is unknown (sample SD is known), use the approach here. If both the sample SD and population SD are unknown, you can’t construct a confidence interval unless you have the standard error or the margin of interval.

[@zunudahal2594]

For t distribution the number should be lesss than 30 than in your last question n=85 how t distribution is applied... Plz explain i didn't get that

[@joshemman]

Yes, most people use t when n is less than 30. However, you can use it for any sample size.

[@spark-to-a-flame8227]

Thank you!

[@joshemman]

You're welcome!

[@sobahlemaseko9189]

Sir im still confused on when to use z ort score

[@joshemman]

You probably haven't watched enough videos. Keep learning. You'll figure it out.

[@anshelphiri1725]

Why have you used t distribution because n is 85 which is greater than 30 i thought it was suppose to be the z distribution

[@joshemman]

In some courses, they use Z because sigma is know. In other courses, they use Z because n is greater than 30. I'm assuming yours is the second case.

[@trumpiden1098]

how i ll understand that i ll use t table or z table :?

[@joshemman]

Some say use Z when n ≥ 30 and some say use Z when σ is known. I will suggest you check your notes, textbook, or with your prof to determine which approach applies in your course.

[@trumpiden1098]

@@joshemman what does this sigma mean in our notes this is written which you wrote that sigma but I don't know what is it can your explain me? Thank you.

[@joshemman]

@@trumpiden1098 Sigma is the population standard deviation. s is used to represent the sample standard deviation.

[@trumpiden1098]

@@joshemman yeah but in questions how will I understand which one is it

[@joshemman]

@@trumpiden1098 If it does not say "population SD", then it is very llikely "sample SD".

[@akullupatriciaopido8268]

Great

[@anurajms]

ty

[@olamidesubair4953]

When n is greater than 30 ain’t you supposed to use z table???

[@joshemman]

Some texts use Z when n > 30, and some don't. If your course says use Z, then do it.

[@ChifundoMandondo]

The margin of error is supposed to be 0.90369 multiply by 2.2140405

[@joshemman]

Where did you get 2.2140405 from?

[@ie95_Moh]

If n> 30 then we use Z not t test !!

[@exemplarypersonality6562]

​@@joshemmanis it true that we should use the Z distribution when n is larger than 30? I noticed you use t distribution on both cases

[@joshemman]

​@@exemplarypersonality6562 Some books use Z when n ≥ 30 but some use Z only when population standard deviation is known. I will suggest you follow how it is taught in your course.

[@ChifundoMandondo]

I have found a different margin of error different from yours

[@ShexMhamad111]

Ok

[@MariamaVandijusu]

Teach me please

[@joshemman]

I'm trying 😆