Chi Square Distribution Test of a Single Variance or Standard Deviation

This statistics video tutorial provides a basic introduction of the chi square distribution test of a single variance or standard deviation. It explains how to use it in order to determine whether or not you reject the null hypothesis.
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Matched or Paired Samples t-Test:
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[@TheOrganicChemistryTutor]

Statistics - Video Lessons: www.video-tutor.net/statistic.html

[@jumpinsphere]

Watched this video before the exam because I lacked this concept even my prof explaining it. Really appreciate your video

[@_M_D_M_]

Excellent. One suggestion, please rename your video to explicitly say it is a Left Tail Chi-Square test. We don't have many videos on KZbin solving this problem. It will be very easy to search. I reached here after 7-8 unwanted videos. Thanks.

[@samuelolonana-rt7mi]

What a nice one ... I like the way he tackle the question ... Is very easy than the way our lecturer taught us 😂

[@datboy_gabriel]

Thank you so much, this is really helpful. God Bless You👐

[@PunmasterSTP]

Chi square distribution? More like "Super video; thanks for the information!" 👍

[@virgojake4531]

I've got a Statistics exam for my Finance degree tmr guys. Wish me luck

[@Henqi]

Excellent quality content, thank you!

[@laurenadams474]

so much better than my professor

[@unknownn1073]

What if your degrees of freedom is not on the table, how do we know what dof to choose from, for example if it’s in between of two, how do we know which one to choose?

[@killthedark7283]

degree of freedom is n-1, in this case, is df=20-1=19. If you have 10000 samples,then 10000-1=9999.

[@tylersoltmannowski3680]

My friend, the most relevant points that are crucial for your procedure are skipped. It will help your viewers when you step deeper into the mathematical details.

[@dawnjane]

I love this video, it was really helpful but is it possible to get examples where a right-tailed and two-tailed test is used? Also, I know that when getting that in this video the critical chi-square value is 10.117 but what's the reason we don't use the intersecting value between the alpha value and degree of freedom? Cause I've seen some articles that say you use the intersecting value between the alpha value and degree of freedom but then don't actually use it, instead they use AR to sort of substitute the alpha value in a chi-square distribution table.

[@Bamanepharm]

actually am kinda confused too,and when you use alpha you get a different value

[@AbleBrawa]

Thanks❤👑👑👑

[@abhishek90101]

in this question we have the population sd(standard deviation) as well as sample sd so why are we not doing the Z test?

[@The-cyber-imbiber]

Chi square is correct because variance is not normally distributed (since it cant be less that zero)

[@--ShivaS]

T test and Z test follows normal distribution , whereas chi square test can be done for non symmetric distributions .

[@Shahd-y3q]

Thannkk uuuu

[@Bamanepharm]

some clarity,when reading from chi square table, which figure do we use 0.05 or 0.95 because in the first example we used 0.05

[@sserwaddaderrick1523]

We read the area to the right !! In the first example it was 0.05 In the second it’s 0.95 coz the alternative hypothesis changes to < it’s skewed to the left

[@sserwaddaderrick1523]

We read the area to the right !! In the first example it was 0.05 In the second it’s 0.95 coz the alternative hypothesis changes to < it’s skewed to the left

[@Bamanepharm]

thanks bro,but I ask for more highlights it really challenges when when it comes to whether we use 5% or 95%,,,​@@sserwaddaderrick1523

[@Lungsiyene]

Thanks

[@TheMetalalien]

I have a quesion : how do you decide how big the rejection area is?

[@wintersolstice4250]

I'm wondering that too unless he forgot to add it into the problem...

[@Xcalzibur]

Generally it is something given within the problem, if not then you can assume it's 0.05 / 0.95 because that's a typical value used

[@loureenvillarosa223]

you can find it using 1- alpha

[@dawnjane]

not really sure if this is helpful right now but if you're given the level of confidence instead of the level of significance then you can get the value of the rejection region by using: 1 - level of confidence = rejection region.

[@dawnjane]

also, from my understanding, the critical value is the rejection region

[@AllenDende]

i just want to confirm how do you assign your Ho and H1 conditions, which logic is used to assign Ho to that corresponding condition

[@mrright2533]

a professor believes this value to be less, that gives you the H1, the standard deviation is 8.6; that gives u the H0

[@horiix7868]

what subject is this ?

[@fynnsvideos]

Statistics

[@yeldossholtan]

I'm new to this subject, but i can't follow formula's logic here. Consider that professor sampled 1000 tests and got 6.9 std. More samples means more significance, so i would believe std is around 6.9. But chi square value would be very big, so we don't reject null hypothesis?? I'm so confused

[@tush89]

What if hypothesis is two tailed? Then what will be the alpha?

[@rradical4714]

that is my question too, wont it be half alpha?

[@russellkemmit8476]

@@rradical4714 2.5 on the left and right

[@drismail469]

Thank you şair but can you explain why variance is square SD

[@yingee8034]

why are we dealing with variance pls

[@PunmasterSTP]

Why not? It's just what this particular example asked for, and I have seen stats questions like it before.

[@sithembilemthimkhulu6229]

Sir i find it diffult to understand isn't our altetnative hypothesis negative since it's less??

[@finotips]

here number cant be negative as it bounded by zero since log normal distribution

[@kailashks901]

6.9... nice

[@Dlowr7]

I have to make a chi square for my biology lab on our plant growth experiment of green beans in different types of soil. I don't understand where to start. How would I know what expected values for green bean growth are? It doesn't make any sense.

[@Agagnier]

Expected = row total × column total / n (AKA total total)

[@evansnyman6729]

Thank you for the informative videos, but PLEASE, as a maths teacher, say your decimal fractions correctly! 12.23 is "Twelve point two three" and NOT "twelve point twenty three"!!!!! Or how would you express 12.023 for example? PLEASE!

[@Bamanepharm]

but the critical value is 30.14,and so we reject the null hypothesis

[@samuraigolfer6919]

But why.

[@mel-kr2xu]

why did u use 0.95 instead of 0.05

[@fatimahilyas6433]

How do you know when the null hypothesis rejected...sometime less than critical value but sometime greater....?

[@jinnjinn5567]

left-tail test if Ha < x (to left of z-critical is rejection region) H₀ ≥ x right-tail test if Ha > x (to right of z-critical is rejection region) H₀ ≤ x two-tail test if Ha ≠ x (left of lower z-critical or right of higher z-critical is rejection region) H₀ = x

[@jinnjinn5567]

or in this case, just replace z with calculated chi value

[@laurenadams474]

goated so goated

[@laurenadams474]

king

[@darspiok]

why do you sometimes square the sample​ variance and other times you dont?

[@amiefelisha7633]

in my own opinion, I just square the sample variance when it has only one tailed but if it is two tailed I don't. I hope it helps

[@abands5082]

Is the rejection value always .05 and .95

[@Xcalzibur]

It can be anything, but a typical value is .05/.95

[@tomatrix7525]

Nope! JG seems to use that value alot though. It can technically be anything, but we generally see 90% and up.

[@Mushgid133]

@@Xcalzibur But how has the Critical Value been derived- on 0.95 or 0.005?? I thought it 95% will produce 30.14 critical value while 5% Significant Level will provide 10.11.

[@ajjepriya2521]

Question wasn't clarity to visible.. otherwise it's 👌...

[@prashanttimalsina5462]

.

[@ig_sussybaka]

saaar thoda thoda hinti aata