Thanks! I have to laugh because at this point in time (2011!!) I was videoing this while holding an IPhone. My my my, how far we've come! Glad the old videos are still useful!
thank you, I found a online test that had questions. However, the answers given came out different from what I learned from your RUclips video. Answers 6) D 7) B. When you solve them you will see why I was a little lost when practicing that test. Find the t-value. 6) Find the critical t-value tα/2 that corresponds to 95% confidence and n = 16. A) 2.947 B) 2.131 C) 2.602 D) 1.753 7) Find the critical t-value tα/2 that corresponds to 90% confidence and n = 15. A) 2.145 B) 1.345 C) 2.624 D) 1.761
Thank you so much for this video! I can't understand my college stats TA at all, and this video not only helped me figure out my calculator but explained how to get the answer/what we need to get there. Thanks!!
Awesome lady! This totally helps with Statistics alot. Book gives vague instructions. Stephanie gives precise step-by-step walkthrough. 10/10 +subscribe for an awesome job :)
Good and important question. If you are doing a two-sided test, then you need to take your Significance Level (alpha) and divide it between the two tails of the distribution. If alpha=0.05, then each tail has 0.05/2 = 0.025 in it. That means the critical value in the upper tail will have 97.5% of the area (or probability) below it.
Thanks so much, I'm taking stats online and the table becomes unusable during tests since it's in the textbook. You think they would show you how to find it without a table because it's not available during testing but noooo. You're a life saver
Have a look at about time 0:58. The calculator wants you to put in the area below the value you want. Since we split the alpha into the two tails, that means under our critical value we have 2.5 + 95 = 97.5.
For a 95% confidence interval for the mean, you have 19 degrees of freedom. You'll have 0.025 in each of your two tails. If you do invT(.975,19), that will give you the correct critical value of 2.093. Note that the 1.725 is incorrect because you forgot to do degrees of freedom (and used sample size instead) and you forgot to split the alpha into the two tails since you wanted a confidence interval. Hope that helps!
@@spendingsavingwithkeetha2505Let's see if we can clarify. When you have a 95% confidence interval, your alpha level is 0.05, which gets split equally into two tails. So, 0.05/2 = 0.025. The calculator wants the area under the curve to the left of the right tail. This area means take 0.025 off of 1 to get 0.975. That is, there is 0.975 to the left and 0.025 to the right.
Watching this video, I noticed you're using a Ti-84Plus. I am also using a Ti-84Plus, but I do not have the "invT" as option 4 under "DISTR". My menu skips "invT" and lists "tpdf" as my 4th choice in that menu. I wonder if there is a way to add this function to my calculator...
Glad it helped! I'm not teaching the class at the moment, but if there are obvious calculator tutorials you think would be helpful, feel free to shoot me some suggestions for future videos.
Keisan, I know! Kind of irritating. Depends on how technical you want to get, but the comment below from mg556linked talks about programming that as a function
For a two-sided test or CI, you split your alpha between the two tails of the distribution. This means you want the critical value that has 1-alpha/2 below it and alpha/2 above it. If you have a one tail test or CI, it is similar but with alpha in one tail and 1-alpha on the other side.
Hi Tom, For finding a critical value, we use a distribution that has mean 0. If you are working on a different situation, feel free to drop it here, and I'll see if I can help.
I figured it out. Some of the older Ti-84Plus calculators, shipped without the "invT" function, but you are able to program it into the older Ti-84 and Ti-83. It's a very short program. Search@youtube: "Programming invT into a Ti 83 or Ti 83+ Calculator"
How do you find the degrees of freedom for a data set ?? I have the numbers 6,9,6,1,5,11,5,9,8.. And the question on my Hw asks "For the data set given below the sample variance will be computed. How many degrees of freedom are there ?"
If you estimating the variance using a sample variance, the degrees of freedom are the sample size minus one. The minus one comes from the fact that you also have to estimate the mean in the calculation.
If you estimating the variance using a sample variance, the degrees of freedom are the sample size minus one. The minus one comes from the fact that you also have to estimate the mean in the calculation.
When I click on invt it brings me to a set that is asking me for area and df. how do you get it to just show up on your screen like that? @Stephanie A. Santorico, Ph.D.
Hi Franko. I don't have access to the calculator at the moment, but if it is giving you that menu, you should be able to enter the same information I typed to get your answer. Good luck!
If you have a t value that is in the lower half of the distribution, it will be negative. This is since the distribution is centered at 0. If you give me your example, I can give you more guidance.
this si why my homework has: Find the critical value t α/2 corresponding to a 95% confidence level. answer is : 2tα/2 = 2.01 says its correct? with? why does she has 2.06?
What is your sample size so we know the degrees of freedom to use? And, is this for a one sample t-test? For example for a sample of size 26 and a one sample t-test, the degrees of freedom would be 26-1=25. For a t value with a 0.05/2=0.025, that would give you a t=2.06.
Looks like an error in their solution. The answer to 6 should be 2.131 or B and the answer to 7 should be 1.761 or D. Maybe they flipped them in the answer key.
When you construct a 95% confidence interval, imagine taking the T distribution (bell-shaped) curve and dividing its area into 2.5% (lower tail) + 95% (middle) + 2.5% (upper tail). The 0.975 corresponds to the division between the upper tail and the middle (2.5%+95%). The value that corresponds to this split of the curve is what you need for critical value.
For a two-sided confidence interval, you need to 1) divide your alpha by 2 then 2) subtract this from 1. This means there is 1-alpha/2 area under the critical value and alpha/2 above it.
The 0.025 corresponds to the area of the t-distribution above (to the right) of the t-value and the 0.975 corresponds to the area below (to the left). Some tables use one and some another. This table gives the below, as well as the one-tail and two tail above probabilities: www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwiN4KCv9KziAhUEsZ4KHWjtBhEQjRx6BAgBEAU&url=http%3A%2F%2Fwww.ttable.org%2F&psig=AOvVaw2-Zq0O7YbUxPcSRz_yaB5M&ust=1558537929558478
Have a look at 0:53 of the video. If you are constructing a 95% confidence interval, you split the left over 5% into two equal tails. So, each tail is 2.5%. The way many tables are formated is they given you the t-value that corresponds to the area under (or to the left of it). Here, that would be 0.25 + 0.95 = 0.975. Hope that makes more sense.
+maimuna hassan For a confidence interval, you evenly split your alpha into the two tails. So, here alpha = 0.05. Divided by 2 is 0.025. This means you are looking for the value with .025+.95 or .975 of the probability below it and .025 above it. Hope that helps! Reply
This depends on your table, but typically you are looking for a critical value in the table that corresponds to a specific tail probability and degrees of freedom.
Ah thanks! BTW you might want to try my updated playlist where I improved the technology a bit...no more wobbly hand holding of the iphone! Ha! Good luck with that math.
Hi Marina! Yes, this is an issue for some. See the comment below by mg556linked. If you really want to be able to do this on your calculator, you have to program it on yourself. If not, you may want to stick with a t-table for use in class. Outside of class most software, including Excel, can find a t critical value for you. Good luck!
@mellowguy024 Glad it helped! There's a ton of videos on RUclips to help out, most probably better in tech value than mine...but if it gets the point across, then I suppose it serves the purpose! Good luck with your class.
This makes me sad to hear. Stats touches lots of our lives, like right now in how vaccinations are effective. Fun stuff here if you want to change your mind: www.significancemagazine.com/
Stuck in quarantine doing stats. No teacher, got to learn it myself. This really helped.
Glad it helped. Hope you are staying well!
@@SASantorico Same here! This really helped! Thank you so much
yoooo same!
Dude fr this is fucking bullshit. What am I paying for
“why a college degree is worthless” popping up in my recommended while i’m struggling over this stats homework gotta be a sign from god..
You literally just summed up my 40-minute lecture into 3 minutes, thank you 🙏
Yay! Now if I could give you those 37 minutes back, I would :-)
Hard to imagine why anyone would "thumbs down" this helpful, free demonstration. My students loved it.
Thanks! I have to laugh because at this point in time (2011!!) I was videoing this while holding an IPhone. My my my, how far we've come! Glad the old videos are still useful!
9 years later still helpful. thankyou!!
Excellent!
Why was it so hard to find someone explaining how to do this? Thank you so much you might have saved my exam
Glad these old videos still have use! Good luck on your exam!
You’re amazing at explaining things comprehensively. You definitely helped me. You’re voice is beautiful and I have a crush on your voice now.
thank you so much been spending an hour trying to find how to do the margin of error for a confidence interval
Glad to see my old videos are still helpful!
9 years later and still helping kids pass college stats
#bestCommentEver
Thank you! The only place on the internet I could actually find a correct example!
You're an awesome person for posting this, literally saved me so much time referring back to my t table
thank you, I found a online test that had questions. However, the answers given came out different from what I learned from your RUclips video. Answers 6) D
7) B. When you solve them you will see why I was a little lost when practicing that test.
Find the t-value.
6) Find the critical t-value tα/2 that corresponds to 95% confidence and n = 16.
A) 2.947 B) 2.131 C) 2.602 D) 1.753
7) Find the critical t-value tα/2 that corresponds to 90% confidence and n = 15.
A) 2.145 B) 1.345 C) 2.624 D) 1.761
Thank you!! your videos helped me understand how to use my calculator and how to find the values for my final tonight! tysm!!!
fantastic, thank you!
Thank you so much for this video! I can't understand my college stats TA at all, and this video not only helped me figure out my calculator but explained how to get the answer/what we need to get there. Thanks!!
THANK YOU SO MUCH! You just saved me from a huge headache about figuring this out. Thank you again, very very helpful :)
Very helpful. Thank you!
Thank you so much
thank you- from the future
Whoa! I hope that was a reference to my old school 2011 hand held recording on an iPhone ;-)
thank you so much , without this explanation, i was going to tomorrow's test blindly.
thanks again and keep it up
Thank you. I was having the hardest time finding how to do this without a table.
Had a big smile when I inputted my numbers and got the right answer on my homework :) Thank you :)
Awesome lady! This totally helps with Statistics alot. Book gives vague instructions. Stephanie gives precise step-by-step walkthrough. 10/10 +subscribe for an awesome job :)
Hope you got this figured out. The critical value is the t-value that corresponds to significance level or alpha level for your test.
Thank you so much for posting this video. Helped me out a ton.
Good and important question. If you are doing a two-sided test, then you need to take your Significance Level (alpha) and divide it between the two tails of the distribution.
If alpha=0.05, then each tail has 0.05/2 = 0.025 in it. That means the critical value in the upper tail will have 97.5% of the area (or probability) below it.
Great! Always good to hear.
Thanks so much, I'm taking stats online and the table becomes unusable during tests since it's in the textbook. You think they would show you how to find it without a table because it's not available during testing but noooo. You're a life saver
Have a look at about time 0:58. The calculator wants you to put in the area below the value you want. Since we split the alpha into the two tails, that means under our critical value we have 2.5 + 95 = 97.5.
This just saved me. I have a final tomorrow and had to return my textbook with the critical value table
gang c c l
gtzdnj
For a 95% confidence interval for the mean, you have 19 degrees of freedom. You'll have 0.025 in each of your two tails. If you do invT(.975,19), that will give you the correct critical value of 2.093. Note that the 1.725 is incorrect because you forgot to do degrees of freedom (and used sample size instead) and you forgot to split the alpha into the two tails since you wanted a confidence interval. Hope that helps!
She threw me off with 0.975
@@spendingsavingwithkeetha2505Let's see if we can clarify. When you have a 95% confidence interval, your alpha level is 0.05, which gets split equally into two tails. So, 0.05/2 = 0.025. The calculator wants the area under the curve to the left of the right tail. This area means take 0.025 off of 1 to get 0.975. That is, there is 0.975 to the left and 0.025 to the right.
It worked out! Thanks ma`am
10 years old and the video is still giving back! Glad it worked out.
This is for a two sided test. for a one sided test, use alpha not alpha/2
Indeed!
Thank you for posting this.
Thank you!
Thanks! Exactly what I needed.
Watching this video, I noticed you're using a Ti-84Plus. I am also using a Ti-84Plus, but I do not have the "invT" as option 4 under "DISTR". My menu skips "invT" and lists "tpdf" as my 4th choice in that menu. I wonder if there is a way to add this function to my calculator...
Glad it helped! I'm not teaching the class at the moment, but if there are obvious calculator tutorials you think would be helpful, feel free to shoot me some suggestions for future videos.
Keisan, I know! Kind of irritating. Depends on how technical you want to get, but the comment below from mg556linked talks about programming that as a function
stats are my life♥ except AP stats is hella hard. thanks for the help.
Glad it helped and that you didn't get queasy from my handheld iPhone video :-D Good luck with the semester!
Glad it helped! Good luck with AP.
This is amazing, I'm not sure if the table will be included on my test, so its nice to know how to find it on my calculator.
Thank you!
Fantastic! Glad you figured it out. I'll be sure to save the reference for my students that end up with this issue.
Where does the .975 come from ?
For a two-sided test or CI, you split your alpha between the two tails of the distribution. This means you want the critical value that has 1-alpha/2 below it and alpha/2 above it. If you have a one tail test or CI, it is similar but with alpha in one tail and 1-alpha on the other side.
what if you don't have the population mean?
Hi Tom, For finding a critical value, we use a distribution that has mean 0. If you are working on a different situation, feel free to drop it here, and I'll see if I can help.
Thank you, hard to find a video walking through this.
Glad to help!
Correct answers will do that. Good job!
Thanks chief now i can do my homework
I figured it out. Some of the older Ti-84Plus calculators, shipped without the "invT" function, but you are able to program it into the older Ti-84 and Ti-83. It's a very short program. Search@youtube: "Programming invT into a Ti 83 or Ti 83+ Calculator"
short and sweet video thank hoyu
Glad they help!
Thanks for the help!
It is possible with fx-991ES calculator?
I don't have one to test it out, but this might help: ruclips.net/video/wviiOngfqWc/видео.html
Thank you. I like your ring by the way.
You're the best, thankyou!
How do you find the degrees of freedom for a data set ?? I have the numbers 6,9,6,1,5,11,5,9,8.. And the question on my Hw asks "For the data set given below the sample variance will be computed. How many degrees of freedom are there ?"
If you estimating the variance using a sample variance, the degrees of freedom are the sample size minus one. The minus one comes from the fact that you also have to estimate the mean in the calculation.
If you estimating the variance using a sample variance, the degrees of freedom are the sample size minus one. The minus one comes from the fact that you also have to estimate the mean in the calculation.
Reading this late but thanks anyway.. I did however figure it out.
When I click on invt it brings me to a set that is asking me for area and df. how do you get it to just show up on your screen like that? @Stephanie A. Santorico, Ph.D.
Hi Franko. I don't have access to the calculator at the moment, but if it is giving you that menu, you should be able to enter the same information I typed to get your answer. Good luck!
Why does my output always come out negative? I think my calculator is configured differently...
Hmm, interesting. So if you do invT(.975, 24), you are getting a negative value? (Specifically, -2.06...?)
Thank you, you are too smart for me.
How did you determine the 97.5% below?
thank you so much, GREAT explanation!:)
Find the critical value t-value tα/2 for 95% confidence interval with n = 20
Is the answer A: 2.093 or B: 1.725
Please rply as soon as possible.
Thank you so much, this video helps me a lot XD
Fantastic! Hopefully it was general enough and not too specific to my class and text. Good luck with you...class and/or analyses.
Thank you :) taking MTH244 Probability and Statistics 2 in Oregon. Agresti doesn't explain well but you do so thanks :)
super
You just saved me !!
XxPrincessKimoraxX yay! There are a few more recent videos I have. Feel free to check them out if you need more help.
Where did you get 97.5 from? sorry lol im taking an online course and am pretty lost
Why does it come out negative sometimes when it supposed to be positive
If you have a t value that is in the lower half of the distribution, it will be negative. This is since the distribution is centered at 0. If you give me your example, I can give you more guidance.
thank you!!
this si why my homework has: Find the critical value t α/2 corresponding to a 95% confidence level.
answer is : 2tα/2 = 2.01 says its correct? with? why does she has 2.06?
What is your sample size so we know the degrees of freedom to use? And, is this for a one sample t-test? For example for a sample of size 26 and a one sample t-test, the degrees of freedom would be 26-1=25. For a t value with a 0.05/2=0.025, that would give you a t=2.06.
25 - 1= 24
@@itsnotmeitsyou4582 For 24 degrees of freedom, the t-value to use for a 95% confidence level is 2.064 rounded to 3 decimal places.
thank you so so much for the help!
Your a life saver! :)
Thank you so much!
Thanks!
Looks like an error in their solution. The answer to 6 should be 2.131 or B and the answer to 7 should be 1.761 or D. Maybe they flipped them in the answer key.
Where did you get .975 from? why is it that?
When you construct a 95% confidence interval, imagine taking the T distribution (bell-shaped) curve and dividing its area into 2.5% (lower tail) + 95% (middle) + 2.5% (upper tail). The 0.975 corresponds to the division between the upper tail and the middle (2.5%+95%). The value that corresponds to this split of the curve is what you need for critical value.
how did you get 97.5 again?
For a two-sided confidence interval, you need to 1) divide your alpha by 2 then 2) subtract this from 1. This means there is 1-alpha/2 area under the critical value and alpha/2 above it.
im confused n= 25 1- 25 = 24 , then 1 - 0.95 = 0.5 Div by 2 = 0.025! not 97.5?
The 0.025 corresponds to the area of the t-distribution above (to the right) of the t-value and the 0.975 corresponds to the area below (to the left). Some tables use one and some another. This table gives the below, as well as the one-tail and two tail above probabilities: www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwiN4KCv9KziAhUEsZ4KHWjtBhEQjRx6BAgBEAU&url=http%3A%2F%2Fwww.ttable.org%2F&psig=AOvVaw2-Zq0O7YbUxPcSRz_yaB5M&ust=1558537929558478
Wtf did we get .975? I’m so confused. This doesn’t work
Have a look at 0:53 of the video. If you are constructing a 95% confidence interval, you split the left over 5% into two equal tails. So, each tail is 2.5%. The way many tables are formated is they given you the t-value that corresponds to the area under (or to the left of it). Here, that would be 0.25 + 0.95 = 0.975. Hope that makes more sense.
great help thanks!
Glad it helped!
I don't have the invT option on my calculator, I have a ti-84 plus...what do I do!?
@mellowguy024 Any chance you're going to school at Renton Tech?
Where'd you get 97.5 ?
+maimuna hassan For a confidence interval, you evenly split your alpha into the two tails. So, here alpha = 0.05. Divided by 2 is 0.025. This means you are looking for the value with .025+.95 or .975 of the probability below it and .025 above it. Hope that helps!
Reply
1 hour scouring through my book with no results - then 90 seconds of a video with great results. WTF am I paying my school for?!?
No Invt( on ti83 calculator :(
I guess I should've spent the big bucks on the 84 :/
You guys can program it!
Cameron Gunter how can you program it?
Look up the video on RUclips. There's this lady w an accent and the videoz 12 mins long. I programed it and I werrrrks!!!
so what number are we looking up on the table?
This depends on your table, but typically you are looking for a critical value in the table that corresponds to a specific tail probability and degrees of freedom.
Thank you nice lady!!!!
Thank you so much. (:
Ah thanks! BTW you might want to try my updated playlist where I improved the technology a bit...no more wobbly hand holding of the iphone! Ha! Good luck with that math.
Hi Marina! Yes, this is an issue for some. See the comment below by mg556linked. If you really want to be able to do this on your calculator, you have to program it on yourself. If not, you may want to stick with a t-table for use in class. Outside of class most software, including Excel, can find a t critical value for you. Good luck!
Awesome!!
@mellowguy024 Glad it helped! There's a ton of videos on RUclips to help out, most probably better in tech value than mine...but if it gets the point across, then I suppose it serves the purpose! Good luck with your class.
life saver!
how to find t crit on ti-89?
can you do this on a casio
Stats is so pointless unless you’re a stats major
This makes me sad to hear. Stats touches lots of our lives, like right now in how vaccinations are effective. Fun stuff here if you want to change your mind: www.significancemagazine.com/
thank you